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United States Patent |
6,044,076
|
Yamamoto
|
March 28, 2000
|
Network system for transmitting a plurality of channels, and node
device, packet transmission method, terminal equipment connection table
generation method, and connection information registration method used
in the system
Abstract
A source terminal equipment connected to a node device transmits a packet
by appending a section for designating the channel to be used upon
relaying the packet by the node device to the packet. The relaying node
device determines the channel used upon outputting the packet by looking
up the value in the section for designation of the channel. The source
terminal equipment transmits the packet by appending relaying number
information indicating the number of relayings of the packet to the
packet. Each node device looks up the relaying number information upon
looking up the value in the section for designation of the channel. When
each node device outputs a packet to a terminal equipment using a
separation device for separating the packet toward the sub transmission
path side, the node devices determines, based on the relaying number
information, whether or not it separates the packet. This invention also
discloses a method of generating a terminal equipment connection table and
a method of registering connection information using the above-mentioned
transmission method.
Inventors:
|
Yamamoto; Mitsuru (Yokohama, JP)
|
Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
|
659933 |
Filed:
|
June 7, 1996 |
Foreign Application Priority Data
| Jun 09, 1995[JP] | 7-168237 |
| Jun 20, 1995[JP] | 7-176780 |
| Jun 20, 1995[JP] | 7-176781 |
| Jul 03, 1995[JP] | 7-189785 |
Current U.S. Class: |
370/392; 370/431; 370/464; 398/1 |
Intern'l Class: |
H04J 014/02 |
Field of Search: |
370/389,392,394,60,248,249,351,400,401,402,409,410,406,431,464
395/377,280
359/124,115,117,118,125,127,128
|
References Cited
U.S. Patent Documents
5422881 | Jun., 1995 | May et al. | 370/60.
|
5517500 | May., 1996 | White et al. | 370/85.
|
5546387 | Aug., 1996 | Larsson et al. | 370/60.
|
5577028 | Nov., 1996 | Chugo et al. | 370/409.
|
5630151 | May., 1997 | Muramatsu et al. | 395/377.
|
5675578 | Oct., 1997 | Gruber et al. | 370/248.
|
5708659 | Jan., 1998 | Rostoker et al. | 370/392.
|
Other References
IEEE Network, vol. 6, No. 4, Jul. 1992, pp. 20-32, Mukherjee, "WDM-Based
Local Lightwave Networks Part II: Multihop Systems".
|
Primary Examiner: Vu; Huy D.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. A network system for connecting node devices through a plurality of
channels, wherein a node device comprises:
receiving means for receiving, from at least one of the plurality of
channels, a packet that includes number information indicating a number of
relayings based on a number of node devices that are to relay the packet
from said node device to a destination node device;
determination means for determining a channel for transmitting the packet
from the plurality of channels for connecting said node device and a first
node device based on the number information; and
output means for outputting the packet to an output channel determined by
said determination means.
2. A system according to claim 1, wherein said node device further
comprises rewrite means for rewriting the number information so that
another node device can look up the rewritten number information when the
packet is output toward the other node device.
3. A system according to claim 2, wherein said rewrite means rewrites the
number information by performing a predetermined arithmetic operation on
the number information.
4. A system according to claim 1, wherein the packet includes respective
selection sections containing selection information for determining an
output channel arranged in correspondence with each of the node devices
that are to relay the packet.
5. A system according to claim 4, wherein said determination means refers
to the selection information based on the number information.
6. A system according to claim 4, said node device further comprising
processing means for, when said output means outputs the packet toward
another node device, processing the packet so that a selection section
corresponding to the other node device is located at a predetermined
position in the packet.
7. A system according to claim 6, wherein
the selection sections are arranged at predetermined positions in the
packet in an order corresponding to an order of the node devices that are
to relay the packet, and
said processing means deletes a selection section corresponding to said
node device.
8. A system according to claim 4, wherein said determination means
determines whether or not to look up a selection section based on the
number information.
9. A system according to claim 1, wherein, when the number information
indicates that said node device is the destination node device, said
output means outputs the packet through a sub transmission path to a
terminal connected to said node device.
10. A system according to claim 1, wherein said receiving means can receive
a packet from any of the plurality of channels, and said output means can
output a packet to any of the plurality of channels.
11. A node device used in a network connecting node devices through a
plurality of channels, said node device comprising:
receiving means for receiving, from at least one of the plurality of
channels, a packet that includes number information indicating a number of
relayings based on a number of node devices that are to relay the packet
from said node device to a destination node device;
determination means for determining a channel for transmitting the packet
from said plurality of channels connecting said node device to a first
node device based on the number information; and
output means for outputting the packet to an output channel determined by
said determination means.
12. A node device according to claim 11, further comprising rewrite means
for rewriting the number information so that another node device can look
up the rewritten number information when the packet is output toward the
other node device.
13. A node device according to claim 12, wherein said rewrite means
rewrites the number information by performing a predetermined arithmetic
operation on the number information.
14. A node device according to claim 11, wherein the packet includes
respective selection sections containing selection information for
determining an output channel arranged in correspondence with each of the
node devices that are to relay the packet.
15. A node device according to claim 14, wherein said determination means
refers to the selection information based on the number information.
16. A node device according to claim 14, further comprising processing
means for, when said output means outputs the packet toward another node
device, processing the packet so that a selection section corresponding to
the other node device is located at a predetermined position in the
packet.
17. A node device according to claim 16, wherein the selection sections are
arranged at predetermined positions in the packet in an order
corresponding to an order of the node devices that are to relay the
packet, and
said processing means deletes a selection section corresponding to said
node device.
18. A node device according to claim 14, wherein said determination means
determines whether or not to look up a selection section based o n the
number information.
19. A node device according to claim 11, wherein, when the number
information indicates that said node device is the destination node
device, said output means outputs the packet through a sub transmission
path to a terminal connected to said node device.
20. A node device according to claim 11, wherein said receiving means can
receive a packet from any of the plurality of channels, and said output
means can output a packet to any of the plurality of channels.
21. A method for controlling a node device used in a network connecting a
plurality of node devices through a plurality of channels, said method
comprising the steps of:
receiving, from at least one of the plurality of channels, a packet that
includes number information indicating a number of relayings based on a
number of node devices that are to relay the packet from said node device
to a destination node device;
determining a channel for transmitting the packet from the plurality of
channels connecting said node device to a first node device based on the
number information; and
outputting the packet to an output channel determined in said determining
step.
22. A method according to claim 21, further comprising, at said node
device, a rewrite step of rewriting the number information so that another
node device can look up the rewritten number information when the packet
is output toward the other node device.
23. A method according to claim 22, wherein said rewrite step rewrites the
number information by performing a predetermined arithmetic operation on
the number information.
24. A method according to claim 21, wherein the packet includes respective
selection sections containing selection information for determining an
output channel arranged in correspondence with each of the node devices
that are to relay the packet.
25. A method according to claim 24, wherein said determining step refers to
the selection information based on the number information.
26. A method according to claim 24, further comprising, at said node
device, a processing step of, when said outputting step outputs the packet
toward another node device, processing the packet so that a selection
section corresponding to the other node device is located at a
predetermined position in the packet.
27. A method according to claim 26, wherein the selection sections are
arranged at predetermined positions in the packet in an order
corresponding to an order of the node devices that are to relay the
packet, and
said processing step deletes a selection section corresponding to said node
device.
28. A method according to claim 24, wherein said determining step
determines whether or not to look up a selection section based on the
number information.
29. A method according to claim 21, wherein, when the number information
indicates that said node device is the destination node device, said
output step outputs the packet through a sub transmission path to a
terminal connected to said node device.
30. A method according to claim 21, wherein said receiving step can receive
a packet from any of the plurality of channels, and said output step can
output a packet to any of the plurality of channels.
31. A relay node device for use in a network connecting node devices
through a transmission path in which a plurality of communication channels
are multiplexed and transmitting communication data from a first
communication device connected to a first node device to a second
communication device connected to a second node device, said relay node
device comprising:
receiving means for receiving communication data to which number
information is added, the number information being based on a number of
node devices through which the communication data is transmitted from the
first communication device to the second communication device;
determination means for determining a communication channel for
transmitting the communication data from the plurality of multiplexed
communication channels based on the number information; and
transmitting means for transmitting the communication data through the
communication channel determined by said determination means.
32. A relay node device according to claim 31, wherein when said relay node
device is not the second node device, based on the number information, the
communication data is transmitted to another node device.
33. A relay node device according to claim 31, wherein when said relay node
device is the second node device, based on the number information, the
communication data is transmitted to the second communication device.
34. A relay node device according to claim 31, wherein the number
information is added to a packet by the first communication device.
35. A relay node device according to claim 31, wherein said transmitting
means rewrites the number information as rewritten number information and
then transmits the communication data with the rewritten number
information to another node device.
36. A relay node device according to claim 31, wherein the network connects
the node devices through the plurality of multiplexed channels.
37. A relay node device according to claim 36, wherein channel information
indicating the determined communication channel through which the
communication data is to be transmitted is added to the communication
data.
38. A relay node device according to claim 37, wherein the communication
data is transmitted through the determined communication channel to the
second node device by a node device one node prior to the second node
device.
39. A relay node device according to claim 37, wherein the communication
data is transmitted through the determined communication channel by a node
device adjacent to the first node device.
40. A network system according to claim 1, wherein said determination means
performs the determination when the number information indicates that said
node device is not said destination node device.
41. A node device according to claim 11, wherein said determination means
performs the determination when the number information indicates that said
node device is not said destination node device.
42. A method according to claim 21, wherein said determination means
performs the determination when the number information indicates that said
node device is not said destination node device.
43. A relay node device according to claim 31, wherein
said determination means determines, based on the number information,
whether the communication data is to be transmitted to the communication
device connected to said relay node device or to another node device
connected through the plurality of multiplexed communication channels, and
said determination means performs the determination of a communication
channel when a determination is made to transmit to another node device.
44. A relay node device according to claim 43, wherein when said
determination means determines that the communication data is to be
transmitted to the communication device connected to said relay node
device, said transmitting means transmits the communication data to the
communication device connected to said relay node device.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network system, a node device and a
communication method for the network system and, more particularly, to a
node device for connecting a plurality of terminal equipments, a network
system constituted by a channel multiplex transmission path using a
plurality of channels (wavelengths or the like) for connecting a plurality
of node devices, and a multihop transmission method, in the node device
and the network system, for converting data to be transmitted into a
packet, and relaying and transmitting the packet by a node device or
devices located on the transmission route between the source terminal
equipment and the destination terminal equipment.
The present invention also relates to a terminal equipment connection table
generation method for setting packet addresses, and a connection
information registration method for registering connection information of
the own terminal equipment to the network in another terminal equipment.
2. Related Background Art
In recent years, in order to realize a high-speed network that connects
terminal equipments in correspondence with high-speed terminal equipments,
various kinds of network systems that use an optical wavelength multiplex
transmission path using a plurality of wavelengths have been examined. As
one of these network systems, a multihop network system which relays and
transmits a packet by a node device or devices located on the transmission
route between the source equipment and the destination terminal equipment
is known. This system is explained in "WDM-Based Local Lightwave Networks
Part II: Multihop Systems", Biswanath Mukherjee, IEEE Network, July
(1992), pp. 20-32.
FIG. 1 shows the connection arrangement of node devices 101 to 112 in a
first multihop system. Eight rings are constituted by using eight
wavelengths .lambda.1 to .lambda.8 in a single optical fiber, and each
node device transmits/receives only optical signals of two specific
wavelengths indicated by marks .omicron.. FIG. 2 shows the arrangement of
the node device. Fixed wavelength receiving means I 201 and II 205
respectively receive optical signals of predetermined wavelengths assigned
to each node device. A 3.times.3 exchange SW 202 has three input terminals
and three output terminals. The exchange SW 202 receives a total of three
data, i.e., the two outputs from the two fixed wavelength receiving means
201 and 205, and transmission data output from a packet processing unit
208 to another node device via a sub transmission path, and outputs these
data to one of FIFOs I 203 and II 206, and the packet processing unit 208
connected thereto via the sub transmission path. The FIFOs I 203 and II
206 temporarily store data of optical signals transmitted from fixed
wavelength transmitting means I 204 and II 207. The fixed wavelength
transmitting means I 204 and II 207 transmit optical signals at fixed
wavelengths designated for each node device.
FIG. 3 shows the format of a packet to be transmitted in the first multihop
system. Referring to FIG. 3, the packet has an address portion 301
indicating the destination terminal equipment of this packet, and a data
portion 302 to be carried by the packet.
FIG. 4 shows the arrangement of the 3.times.3 exchange SW 202. Referring to
FIG. 4, each of decoders 401 reads the destination address of an input
packet, and outputs, to an SW control unit 402, output designation data
for designating one of outputs X, Y, and Z as an output destination of
this packet. The SW control unit 402 performs arbitration control on the
basis of the output designation data output from the decoders 401, so that
packets input from inputs A, B, and C do not collide in a 3.times.3 SW
403, and thereafter, sets connections between the inputs A, B, and C and
the outputs X, Y, and Z of the 3.times.3 SW 403. The 3.times.3 SW 403
outputs packets input from the inputs A, B, and C to predetermined ones of
the outputs X, Y, and Z under the control of the SW control unit 402.
In the node device of the first multihop system, packets output from three
means, i.e., the fixed wavelength receiving means I 201 and II 205 and the
packet processing unit 208 are input from the inputs A, B, and C. Each
decoder 401 reads the address of the destination terminal equipment of an
input packet, one of the fixed wavelength transmitting means I 204 and II
207 as an output destination for transmitting a packet at a predetermined
transmission wavelength corresponding to the reading address or the packet
processing unit 208 for performing packet reception processing is
selected, and the connections between the inputs and outputs of the
3.times.3 SW 403 are set under the control of the SW control unit 402.
Then, the packet is output from a desired output destination.
In the network system using the above-mentioned node device, for example,
when a packet is to be transmitted from the node device 102 to the node
device 109, if the transmission wavelength of the node device 102 is
different from the reception wavelength of the node device 109, the node
device 105 located therebetween performs a relaying operation for changing
the wavelength of the packet and transmitting the packet. More
specifically, the node device 102 serving as a source transmits a packet
using an optical signal of the wavelength .lambda.3. The optical signal of
the wavelength .lambda.3 is received by the fixed wavelength receiving
means of the node device 105, and is temporarily stored by the 3.times.3
exchange SW 202 in the FIFO corresponding to the fixed wavelength
transmitting means of the wavelength .lambda.1. Then, the packet is
transmitted from the fixed wavelength transmitting means as an optical
signal of the wavelength .lambda.1. The optical signal of the wavelength
.lambda.1 is received by the fixed wavelength receiving means of the node
device 109 serving as a destination, and is input to the packet processing
unit 208 via the 3.times.3 exchange SW 202. The packet is then subjected
to predetermined reception processing in the packet processing unit 208.
In this manner, in the node device which relays and transmits a packet,
the transmission wavelength is switched to the wavelength corresponding to
the destination address 301 decoded by the corresponding decoder 401, and
the packet is transmitted at the switched wavelength.
The arrangement of a node device used in a multihop system invented by the
present inventors will be described below for the purpose of a reference.
FIGS. 5A and 5B show the arrangement of a node device of this example.
Referring to FIGS. 5A and 5B, a control section 501 controls the reading
operations of buffers I 520 to VIII 527, and also controls the
transmission wavelengths of variable wavelength transmission units I 528
to VIII 535. An optical fiber 502 serves as an optical wavelength
multiplex transmission path. A divider 503 divides an optical signal
transmitted from the optical fiber 502 and outputs the divided optical
signal to eight fixed wavelength reception units I 504 to VIII 511. Each
of the fixed wavelength reception units I 504 to VIII 511 receives only a
packet transmitted as an optical signal of a corresponding one of
wavelengths .lambda.1 to .lambda.8. Separation-insertion units I 512 to
VIII 519 have a function of separating packets to be transmitted to sub
transmission paths I 537 to VIII 544 from packet flows output from the
fixed wavelength reception units 504 to 511 and outputting them onto the
sub transmission paths I 537 to VIII 544, and a function of inserting
packets transmitted from the sub transmission paths I 537 to VIII 544 into
the packet flows output from the fixed wavelength reception units 504 to
511. The buffers I 520 to VIII 527 have a function of temporarily storing
packets output from the separation-insertion units 512 to 519. Each of the
variable wavelength transmission 535 converts a packet output from a
corresponding one of the buffers 520 to 527 into an optical signal of a
predetermined one of the wavelengths .lambda.1 to .lambda.8 under the
control of the control section 501, and outputs the converted signal onto
the optical fiber 502 via a wavelength multiplexer 536. These variable
wavelength transmission units are controlled so that multiple variable
wavelength transmission units do not transmit packets using an identical
wavelength. The wavelength multiplexer 536 multiplexes optical signals of
the wavelengths .lambda.1 to .lambda.8 output from the eight variable
wavelength transmission units 528 to 535, and outputs the multiplexed
signal onto the optical fiber 502. The sub transmission paths I 537 to
VIII 544 serve as packet transmission paths between the
separation-insertion units 512 to 519 and terminal equipments I 545 to
VIII 552. The terminal equipments I 545 to VIII 552 are respectively
connected to the sub transmission paths I 537 to VIII 544. These terminal
equipments receive packets output from the separation-insertion units 512
to 519, generate packets to be transmitted to other terminal equipments,
and transmit them to the separation-insertion units 512 to 519 via the sub
transmission paths 537 to 544.
Note that the format of a packet in the second multihop system as the
example is the same that to be transmitted in the above-mentioned first
multihop system.
FIG. 6 shows the arrangement of a network system using the node device of
the second multihop system shown in FIGS. 5A and 5B, and exemplifies a
case wherein four node devices are connected via optical fibers. Node
devices 601 to 604 are equivalent to that shown in FIGS. 5A and 5B, and
eight terminal equipments are connected to each node device via eight sub
transmission paths. Optical fibers 605 to 608 constitute an optical
wavelength multiplex transmission path.
FIG. 7 shows the internal arrangement of each of the separation-insertion
units I 512 to VIII 519 used in the node device of the second multihop
system. The separation-insertion units I to VIII have the same internal
arrangement. Referring to FIG. 7, a decoder I 701 reads a destination
address 301 of an input packet and instructs a demultiplexer 702 as to
whether or not this packet is to be output to an I/F (Interface) unit 703.
The demultiplexer 702 outputs an input packet to the I/F unit 703 or a
FIFO II 705 in accordance with an instruction from the decoder I 701. The
I/F unit 703 outputs a packet output from the demultiplexer 702 onto the
sub transmission path, and outputs a packet input from the sub
transmission path to a FIFO I 704. The FIFOs I 704 and II 705 temporarily
store input packets, and output the stored packets to a selector I 707 in
the input order under the control of an insertion control unit 706. The
insertion control unit 706 controls the reading operations of the FIFOs I
704 and II 705, and instructs the selector I 707 of the FIFO to be
selected, thereby inserting a packet transmitted from the sub transmission
path into a packet flow output from the fixed wavelength reception unit.
The selector I 707 selects the FIFO that stores a packet signal to be
output in accordance with an instruction from the insertion control unit
706.
FIG. 8 shows the detailed arrangement of each of the buffers I to VIII used
in the node device of the second multihop system. Referring to FIG. 8, a
decoder II 801 reads an address portion 301 indicating the destination
terminal equipment of an input packet, and instructs a writing address
counter 802 of the writing start address value of a dual port memory 804
in which the packet is to be written in accordance with the destination of
the packet. The writing address counter 802 sequentially outputs address
signals of the packet to the dual port memory 804 in accordance with the
writing start address value output from the decoder II 801. A reading
address counter 803 sequentially outputs reading address signals of a
packet to the dual port memory 804 using an offset value output from a
buffer control unit in the control section 501 as the reading start
address. The dual port memory 804 independently performs the writing and
reading operations of the packet data 302. The memory region of the dual
port memory 804 is divided in correspondence with the wavelengths to be
used upon transmission.
FIG. 9 shows the arrangement of the terminal equipment. Referring to FIG.
9, an I/F (Interface) unit 901 outputs a packet output from a packet
processing unit 902 onto a corresponding one of the sub transmission paths
537 to 544, and outputs a packet input from the corresponding sub
transmission path to the packet processing unit 902. The packet processing
unit 902 obtains the value of an address portion 301 corresponding to the
destination terminal equipment by looking up a terminal equipment
connection table 903, and writes the obtained value in a predetermined
section of a header, i.e., adds the value to data to be transmitted to
form a packet. Also, the unit 902 removes the header portion of a received
packet input via the I/F unit 901, and performs predetermined reception
processing. The terminal equipment connection table 903 has address
information of the respective terminal equipments connected to this
network system. An input/output unit 904 has an interface function such as
a keyboard, a display device, and the like.
In the second multihop system described above, a packet output from the
source terminal equipment is inserted into a packet flow output from a
corresponding one of the fixed wavelength reception units 504 to 511 by a
corresponding one of the separation-insertion units 512 to 519. The
address of the destination terminal equipment is read by a corresponding
one of the buffers 520 to 527, and the packet is temporarily stored in the
memory region corresponding to the reading address. Thereafter, the packet
is output from a corresponding one of the variable wavelength transmission
units 528 to 535 as an optical signal of a predetermined wavelength, and
is relayed by the node devices present before the node device to which the
destination terminal equipment is connected. In each node device that
performs the relaying operation, the address of the destination node
device is read by the decoders in the separation-insertion units 512 to
519 and the buffers 520 to 527, and the packet is then written in a
predetermined memory region of the dual port memory 804. The stored packet
is transmitted from a corresponding one of the variable wavelength
transmission units 528 to 535 as an optical signal of a predetermined
wavelength. By repeating the relaying operation, a corresponding one of
the variable wavelength transmission units 528 to 535 of the node device
immediately before the node device, to which the destination terminal
equipment is connected, converts the packet into an optical signal of the
wavelength to be received by a corresponding one of the fixed wavelength
reception units 504 to 511 for outputting packets to the
separation-insertion units 512 to 519 to which the sub transmission path
537 to 544 including the destination are connected. The packet output from
the variable wavelength transmission unit is received by the predetermined
fixed wavelength reception unit, and is then output from the
separation-insertion unit to the sub transmission path. Then, the packet
is received by the destination terminal equipment. As described above, in
the second multihop system, in the relaying operation of the node device,
the address 301 of the destination terminal equipment is read, and the
packet is transmitted at the transmission wavelength corresponding to the
reading address, thereby routing a packet to a desired terminal equipment
of a desired node device.
In the first and second multihop systems, since each decoder has a large
hardware scale, as will be described below, each node device becomes
expensive.
FIG. 10 shows the arrangement of the decoder used in the 3.times.3 exchange
SW in the first multihop system shown in FIG. 4 or in the
separation-insertion unit and the buffer in the second multihop system,
and exemplifies an arrangement for decoding the addresses of n terminal
equipments.
Referring to FIG. 10, a latch 1001 has a function of temporarily storing
the destination address portion 301 of an input packet. A decoder
management unit (not shown) writes the addresses of n terminal equipments
respectively in n memories 1002. Comparators 1003 compare the destination
address of the packet temporarily stored in the latch 1001 with the
addresses stored in the memories 1002. When the two addresses coincide
with each other, each comparator 1003 outputs a coincidence signal to a
table address generator 1004. The table address generator 1004 generates a
table address for reading out an output designation table 1005. The output
designation table 1005 stores desired output designation data. The table
address generated by the table address generator 1004 is an address for
reading out a table corresponding to the serial number of the comparator
1003 that generated a coincidence signal, and hence, the output
designation data of the table corresponding to the destination address of
the input packet is read out. Based on this output designation data, the
output destination of the packet to be transmitted using a desired
transmission wavelength, is determined.
As described above, in the decoder with the above arrangement, the
destination address of an input packet is compared with the addresses of
all the terminal equipments connected to the network system, and output
designation data is read out from the output designation table on the
basis of the matching address of the terminal equipment as a result of
comparison. For this reason, the number of required pairs of memories and
comparators must be equal to or larger than the number of terminal
equipments connected to the network system, and the number of table data
stored in the output designation table must also be equal to or larger
than the number of terminal equipments. Furthermore, the table address
generator requires a longer time for generating table addresses as the
number of input coincidence signals increases.
Therefore, the decoder with the above arrangement requires a larger
hardware scale and higher cost and becomes difficult to attain high-speed
address decoding as the number of terminal equipments connected to the
network system increases, thus hampering a high-speed operation of the
network system.
The present invention has been made in consideration of the problems of the
prior art and the example, and has as its object to provide a low-cost
node device by preventing an increase in hardware scale of the node device
by a node device and a communication method which allow to simplify
decoders in the node device, and to realize a high-speed operation of a
network system.
SUMMARY OF THE INVENTION
The present application solves the above-mentioned problems by the
following network system.
(1) A network system for transmitting a packet by connecting a plurality of
node devices via a transmission path for transmitting a plurality of
channels, comprises:
the transmission path; and
a node device comprising:
receiving means for respectively receiving at least two channels of the
plurality of channels; and
output means for outputting a packet received by the receiving means by
selecting one of the at least two channels,
wherein the packet used in the network system has a section for designation
of a channel to be looked up when the packet is relayed by the at least
one node device, and the at least one node device selects the channel used
for outputting the packet by looking up a value in the section for
designation of the channel.
According to this network system, the node device that performs the
relaying operation can determine an output channel by looking up the
section for designation of a channel.
(2) Furthermore, the present application discloses the following
arrangement as an arrangement for efficiently looking up the section for
designation of a channel.
The node device further comprises processing means for processing the
packet so that another node device can look up the section for designation
of the channel to be looked up when the received packet is relayed and
output toward the other node device.
Also, the following arrangements are available.
(3) The section for designation of the channel is arranged in
correspondence with each of the node devices which are to relay the
packet.
(4) A plurality of sections for designation of a channel equivalent to the
channel for designation of the channel are arranged in correspondence with
the node devices which are to relay the packet, and the processing means
processes the packet so that the section for designation of the channel to
be looked up by the other node device is located at a predetermined
position in the packet.
(5) In this case, the plurality of sections for designation of the channel
are arranged at predetermined positions in the packet in an order to be
looked up by the node devices that are to relay the packet, and the
processing means deletes the section for designation of the channel that
has been looked up by the own node device.
(6) The packet has a section for indication of the number of relayings,
which describes relaying number information indicating the number of
relayings of the packet, and
the node device may further comprise determination means for determining,
by looking up the section for indication of the number of relayings,
whether or not the own node device is a node device which should look up
the section for designation of the channel.
(7) Furthermore, when the node device further comprises rewriting means for
rewriting the relaying number information when the received packet is
relayed and output, the information for number of relayings can indicate
the number of relayings of a packet thereafter.
(8) More specifically, the rewriting means performs a predetermined
calculation of the relaying number information.
(9) As another arrangement, a plurality of sections for designation of a
channel equivalent to the channel for designation of the channel are
arranged in correspondence with the node devices which are to relay the
packet, and the packet has a section for indication of the number of
relayings, which describes relaying number information indicating the
number of relayings of the packet, and
the node device further comprises determination means for determining, by
looking up the relaying number information, the section for designation of
the channel to be looked up of the plurality of sections for designation
of the channel, and rewriting means for rewriting the relaying number
information.
(10) An output destination to which the output means outputs the packet may
be selected from the at least two channels and a sub transmission path. At
this time, for example, the terminal equipment is connected to the node
device via the sub transmission path.
(11) In place of allowing the output means to output a packet to the sub
transmission path in (10), the node device may further comprise separation
means for separating a predetermined packet from the packets received by
the receiving means to a sub transmission path. With this arrangement, the
output destination selection load on the output means of the node device
can be reduced.
(12) At this time, if the packet has a section for indication of the number
of relayings, which describes relaying number information indicating the
number of relayings of the packet,
the separation means can determine, by looking up the relaying number
information of the input packet, whether or not the packet is to be
separated.
(13) As the channels to be received by the node device, the node device may
receive only some of the channels used in the network or may receive all
the channels. In either case, channels that can be output from the output
means are preferably common to those to be received by the node device.
This is because the need for using another means for avoiding radio
interferences with other channels can be obviated when the reception
channels are set to common to the output channels.
The present application also discloses the above-mentioned node device.
The present application discloses the following transmission method as a
packet transmission method.
(1) A transmission method for transmitting a packet in a network system
constituted by connecting a plurality of node devices via a transmission
path for transmitting a plurality of channels, comprises the steps of:
transmitting, from a source of a packet, the packet by appending a section
for designation of a channel for designating a channel to be used upon
outputting the packet in at least one of the node devices which are to
relay the packet, to the packet to be transmitted;
determining a channel for outputting the packet by looking up the section
for designation of the channel in at least one of the node devices which
are to relay the packet, and outputting the packet using the determined
channel; and
receiving, by a node device which is to receive the packet, the packet
transmitted using the determined channel.
Also, the present application discloses the following transmission method
as a method of transmitting a packet to a plurality of destinations using
the above-mentioned packet having the section for designation of a
channel.
(2) A transmission method for transmitting a packet to a plurality of
destinations in a network system which connects a plurality of node
devices via a transmission path for transmitting a plurality of channels,
and relays a packet to be transmitted in turn toward a downstream side in
a transmission direction by the plurality of node devices, comprises:
the first step of sequentially transmitting, from a source of a packet,
packets corresponding in number to all the channels received by a node
device, serving as a target node device in the first step, next to a first
node device, which receives the packets transmitted from the source first,
by sequentially designating all the channels received by the node device
next to the first node device in sections for designation of channels for
designating channels used upon outputting, from the first node device, the
packets transmitted from the source; and
the second step of defining a node device next to the target node device in
the first step as a target node device, and sequentially transmitting,
from the source of a packet or packet transmitting means designated before
the second step, packets corresponding in number to all the channels
received by the target node device in the second step by sequentially
designating all the channels received by the target node device in the
second step in sections for designation of a channel for designating
channels used by the target node device in the first step upon outputting
the packets to the target device in the second step,
wherein the transmission method repeats the second step after the first
step.
(3) In this transmission method, the source can receive a packet
transmitted using at least one of the plurality of channels, the plurality
of node devices are connected in a ring pattern, and the source repeats
the second step until the source receives the same packet as the packet
transmitted by itself. With this arrangement, the source (or broadcasting
source) can transmit a packet to all the node devices even when it does
not recognize the number of node devices connected to the network.
(4) Furthermore, in this case, when the source receives the same packet as
the packet transmitted by itself during the second step, the transmission
of the packets ends after the second step which is not completed yet is
completed. With this arrangement, the packet can be received by all the
channels to be received by all the node devices including all the channels
to be received by the node device to which the broadcasting source is
connected.
(5) In order to obtain the same effect as in (4), the following arrangement
may be used. In the first and second steps, the packets transmitted to the
target node device in each of the first and second steps and corresponding
in number to all the channels received by the target node device are
sequentially transmitted in an order in which the target node device
receives the packet transmitted using the channel that can be received by
the source last.
(6) In the first and second steps, the source or the designated packet
transmitting means transmits the packet by appending information for
identifying the target node devices to the packet to be transmitted. With
this arrangement, the node device that relays the packet can easily
discriminate whether or not the own node device is a target node device.
(7) More specifically, the information for identifying the target node
device is relaying number information indicating the number of relayings
of the packet.
(8) As a method of designating the transmitting means, the source or the
designated packet transmitting means appends information for designating
transmitting means for transmitting packets in the subsequent step to one
of the packets to be transmitted in each step.
(9) In the above-mentioned transmission method, the source appends
identification information for identifying the source to the packets to be
transmitted. With this format, the destination terminal equipment that
received the packet or the own source can recognize the source.
(10) A terminal equipment connection table can be generated as follows
using the transmission method of (1). As the network arrangement at this
time, each of the plurality of node devices comprises separation means for
separating a predetermined packet of the packets received using a
plurality of channels to be received by the node device to different
terminal equipments in units of received channels,
the source transmits a packet for notification of the number of node
devices indicating the number of node devices connected to the network as
the packet, and
the method further comprises:
the third step of transmitting, from each of the terminal equipments which
receive the packet for notification of the number of node devices,
information indicating the node device to which the own terminal equipment
is connected and information indicating channels which can be received by
the own terminal equipment, to the source; and
the fourth step of generating, by the source, a terminal equipment
connection table on the basis of the information sent from the terminal
equipments.
(11) In this case, the method further may comprise, as the step of
counting, by the source, the number of node devices connected to the
network system:
the step of sequentially transmitting, from the source, a packet for count
of the number of node devices having relaying number information which
designates the number of relayings by the node devices by sequentially
increasing the number of relayings indicated by the relaying number
information, receiving, by the source, the packet for count of the number
of node devices transmitted by itself, and counting the number of node
devices connected to the network system on the basis of the number of
relayings of the received packet for count of the number of node devices.
(12) Also, in this case, the method may further comprises, as another step
of counting, by the source, the number of node devices connected to the
network system:
the step of sequentially transmitting, from the source, a packet for count
of the number of node devices having a section for describing information
indicating the number of relayings to the next node device, receiving the
packet for count of the number of node devices by a terminal equipment
connected to the next node device, performing a predetermined calculation
for the information indicating the number of relayings by the terminal
equipment, transferring the packet for count of the number of node devices
from the terminal equipment to the next node device, repeating the
transfer operation until the source receives the packet for count of the
number of node devices, and counting, by the source, the number of node
devices connected to the network system on the basis of the information
indicating the number of relayings.
(13) Furthermore, when the source transmits the terminal equipment
connection table generated in the fourth step to the terminal equipments,
other terminal equipments need not generate their terminal equipment
connection tables.
(14) In the transmission method of (1), each of the plurality of node
devices comprises separation means for separating a predetermined packet
of the packets received using a plurality of channels to be received by
the node device to different terminal equipments in units of received
channels, and
the source is one of the terminal equipments, and the packets transmitted
by the source includes information indicating the node device to which the
own terminal equipment is connected, and information indicating channels
that can be received by the own terminal equipment. With this arrangement,
connection information of the own terminal equipment can be transmitted to
terminal equipments connected to the respective node devices.
(15) Furthermore, when the source requests the terminal equipments other
than itself to transmit terminal equipment connection information, the
source can collect terminal equipment connection information.
(16) The present application also proposes the following terminal equipment
connection table generation method.
A terminal equipment connection table generation method in a network system
constituted by connecting a plurality of node devices, each of which can
receive a plurality of channels, and can output packets transmitted using
the receiving channels to different terminal equipments in units of
receiving channels, via a transmission path for transmitting a plurality
of channels, comprises:
the first step of counting, by a first terminal equipment, the number of
node devices connected to the network system;
the second step of notifying the counted number of node devices from the
first terminal equipment to other terminal equipments;
the third step of transmitting, from each of the terminal equipments which
are notified of the number of node devices, information indicating the
node device to which the own terminal equipment is connected and
information indicating channels which can be received by the own terminal
equipment to the first terminal equipment; and
the fourth step of generating, by the first terminal equipment, a terminal
equipment connection table on the basis of the information sent from the
terminal equipments.
(17) The present application also proposes the following connection
information registration method.
A connection information registration method in a network system
constituted by connecting a plurality of node devices, each of which can
receive a plurality of channels, and can output packets transmitted using
the receiving channels to different terminal equipments in units of
receiving channels, via a transmission path for transmitting a plurality
of channels, comprises:
the first step of transmitting, from a first terminal equipment which
requests to register connection information of the own terminal equipment
in other terminal equipments, information indicating the node device to
which the own terminal equipment is connected and information indicating
channels which can be received by the own terminal equipment to other
terminal equipments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing a first multihop system;
FIG. 2 is a block diagram showing the arrangement of a node device used in
the first multihop system;
FIG. 3 is a view showing the format of a packet used in the first multihop
system;
FIG. 4 is a block diagram showing the arrangement of a 3.times.3 exchange
SW of the node used in the first multihop system;
FIG. 5 is comprised of FIGS. 5A and 5B illustrating block diagrams showing
the arrangement of a node device used in a second multihop system;
FIG. 6 is a diagram showing the arrangement of the second multihop system;
FIG. 7 is a block diagram showing the arrangement of a separation-insertion
unit of the node device used in the second multihop system;
FIG. 8 is a block diagram showing the arrangement of a buffer of the node
device used in the second multihop system;
FIG. 9 is a block diagram showing the arrangement of a terminal equipment
used in the second multihop system;
FIG. 10 is a block diagram showing the arrangement of a decoder;
FIG. 11 is a view showing the format of a packet according to the first
embodiment of the present invention;
FIG. 12 is a block diagram showing the arrangement of a 3.times.3 SW, and
FIFOs I and II according to the first embodiment of the present invention;
FIG. 13 is a view showing the format of a packet used in the present
invention;
FIG. 14 is a view showing the format of a packet according to the second
embodiment of the present invention;
FIG. 15 is a view showing the format of a packet according to the third
embodiment of the present invention;
FIG. 16 is a block diagram showing the arrangement of a
separation-insertion unit according to the third embodiment of the present
invention;
FIG. 17 is a block diagram showing the arrangement of a buffer according to
the third embodiment of the present invention;
FIG. 18 is a view showing the format of a packet used in the present
invention;
FIG. 19 is a block diagram showing the arrangement of a buffer according to
the fourth embodiment of the present invention;
FIG. 20 is a view showing the format of a broadcasting packet according to
the fifth embodiment of the present invention;
FIG. 21 is a flow chart showing the operation of a terminal equipment as a
source of the broadcasting packet according to the fifth embodiment of the
present invention;
FIG. 22 is a view showing the format of a broadcasting packet according to
the sixth embodiment of the present invention;
FIG. 23 is a flow chart showing the operation of a terminal equipment as a
source of the broadcasting packet according to the sixth embodiment of the
present invention;
FIG. 24 is a flow chart showing the operation of a terminal equipment for
receiving the broadcasting packet according to the sixth embodiment of the
present invention;
FIG. 25 is a view showing the format of a packet for count of the number of
node devices according to the seventh embodiment of the present invention;
FIG. 26 is a view showing the format of a packet for notification of the
number of node devices according to the seventh embodiment of the present
invention;
FIG. 27 is a view showing the format of a packet for report of the
connection form according to the seventh embodiment of the present
invention;
FIG. 28 is a flow chart showing the operation of a server in the first
process according to the seventh embodiment of the present invention;
FIG. 29 is a flow chart showing the operation of the server in the second
process according to the seventh embodiment of the present invention;
FIG. 30 is a flow chart showing the operation of the server in the second
process according to the seventh embodiment of the present invention;
FIG. 31 is a view showing the format of a packet for count of the number of
node devices according to the eighth embodiment of the present invention;
FIG. 32 is a flow chart showing the operation of a server in the first
process according to the eighth embodiment of the present invention;
FIG. 33 is a flow chart showing the operation of a terminal equipment in
the first process according to the eighth embodiment of the present
invention;
FIG. 34 is a view showing the format of a packet for register request
according to the ninth embodiment of the present invention;
FIG. 35 is a view showing the format of a packet for transfer request
according to the ninth embodiment of the present invention;
FIG. 36 is a flow chart showing the operation of a terminal equipment as a
source of the packet for register request according to the ninth
embodiment of the present invention;
FIG. 37 is a flow chart showing the operation of a terminal equipment for
receiving the packet for register request according to the ninth
embodiment of the present invention;
FIG. 38 is a flow chart showing the operation of a terminal equipment as a
source of a packet for register request according to the 10th embodiment
of the present invention; and
FIG. 39 is a flow chart showing the operation of a terminal equipment for
receiving the packet for register request according to the 10th embodiment
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(First Embodiment)
FIG. 11 shows the format of a packet according to the first embodiment of
the present invention, which is suitably used in the optical communication
method of the first multihop system shown in FIGS. 1 and 2.
Referring to FIG. 11, a header portion 1101 includes sections for
designating the wavelengths to be used in relaying operations of an
optical signal. More specifically, the header portion 1101 includes a
section for designation of the wavelength in use of the first relaying
node device, a section for designation of the wavelength in use of the
second relaying node device, a section for designation of the wavelength
in use of the third relaying node device, sections for designation of the
wavelength in use of the subsequent relaying node devices (not shown) that
perform relaying operations in turn, which sections are used for
designating the wavelengths to be used in the respective node devices, and
a section for identification of the last relaying node device. A data
portion 1102 is carried by this packet. As the value used in each section
of this header portion 1101, "1" is assigned when the shorter one
(.lambda.s) of two wavelengths (.lambda.s, .lambda.e; .lambda.s
<.lambda.e) as the transmission wavelengths of each node device is used,
and "2" is assigned when the longer wavelength (.lambda.e) is used. Assume
that optical wavelengths satisfy
.lambda.1<.lambda.2<.lambda.3<.lambda.4<.lambda.5<.lambda.6<.lambda.7<.lam
bda.8, and the shorter one (.lambda.s) of the two wavelengths to be
transmitted by two fixed wavelength transmitting means I 204 and II 207 of
each node device is transmitted by the fixed wavelength transmitting means
I 204. Similarly, assume that the shorter one (.lambda.s) of the two
wavelengths to be received by two fixed wavelength receiving means I 201
and II 205 of each node device is received by the fixed wavelength
receiving means I 201. Furthermore, in Table 1 below, as the value for
identifying the last relaying node device, "0" is assigned.
TABLE 1
______________________________________
Value in Section for
Designation of Wavelength
Wavelength Used by
in Use of Relaying Node
Relaying Node Device
Device
______________________________________
s 1
e 2
______________________________________
Value in Section for
Identification of Last
Identification of Last
Relaying Node Relaying Node Device
______________________________________
In Case of Last Relaying
0
Node Device
______________________________________
FIG. 12 shows the arrangement of a 3.times.3 exchange SW, and FIFOs I and
II suitably used in a system using an optical communication method
according to the first embodiment of the present invention. Note that
other portions are the same as those in the node device of the first
multihop system shown in FIG. 2. Referring to FIG. 12, a 3.times.3
exchange SW 1201 includes latches I 1202 to III 1204. The latches I 1202
to III 1204 respectively store the contents of the first sections of the
header portions of packets output from the fixed wavelength receiving
means I and II, and a packet processing unit, and output the stored values
to an SW control unit 1205. The value output at this time is "1" or "2"
for instructing the wavelength .lambda.s or .lambda.e in a node device
other than the last relaying node device, or is "0" for identifying the
last relaying node device in the last relaying node device, as shown in
Table 1 above. The SW control unit 1205 performs arbitration control on
the basis of the values output from the latches 1202 to 1204, so that
packets output from the fixed wavelength receiving means I and II, and the
packet processing unit do not collide in a 3.times.3 SW 1206, and then,
outputs each input packet to a desired output destination of FIFOs I 1207
and II 1208, and the packet processing unit. In this packet output
operation, the SW control unit 1205 removes the first section in the
header portion 1101 of an input packet by controlling the first section of
the packet to be not output to the output destination. The 3.times.3 SW
outputs packets output from the fixed wavelength receiving means I and II,
and the packet processing unit to required ones of the FIFOs I and II, and
the packet processing unit. The FIFOs I 1207 and II 1208 temporarily store
packets output from the 3.times.3 SW 1206, and output the stored packets
to the fixed wavelength transmitting means I and II, respectively.
FIG. 13 shows the format of a packet according to the first embodiment,
which packet is suitably used when a packet is transmitted from a node
device 102 to a node device 109 in the first multihop system shown in FIG.
1 using the above-mentioned node device. In FIG. 13, a value "1" for
designating .lambda.s=.lambda.3 as the wavelength to be used is designated
in the section for designation of the wavelength in use of the first
relaying node device in the header portion 1101, and a value "1" for
designating .lambda.s =.lambda.1 as the wavelength to be used is
designated in the section for designation of the wavelength in use of the
second relaying node device. The third section has a value "0" that
indicates the section for identification of the last relaying node device.
In the following description, this packet will be referred to as a packet
A.
The operation for transmitting the packet A shown in FIG. 13 according to
the first embodiment of the present invention will be described below with
reference to FIGS. 11, 12, and 13, and FIGS. 1 and 2. In the following
description, the same constituting elements of different node devices will
be denoted by the same reference numerals in FIGS. 11, 12, and 13 and
FIGS. 1 and 2, for the sake of convenience.
When data to be transmitted to the node device 109 is generated in a packet
processing unit 208 of the node device 102, the packet processing unit 208
forms a packet A by adding a header portion 1101, which designates the
wavelengths to be used in the respective relaying node devices, to the
data, and outputs this packet A to the 3.times.3 exchange SW 1201.
In the 3.times.3 exchange SW 1201, the value in the section for designation
of the wavelength in use of the first relaying node device as the first
section of the header portion 1101 of the packet A is read by the latch
III 1204, and the read value "1" is output to the SW control unit 1205.
The SW control unit 1205 performs arbitration control on the basis of the
values output from the latches I 1202 and II 1203, and the value "1"
output from the latch III 1204, so that packets do not collide in the
3.times.3 SW 1206, and thereafter, sets the 3.times.3 SW 1206, so that the
packet A output from the packet processing unit 208 is output to the FIFO
I 1207. In this packet output operation, the SW control unit 1205 removes
the section for designation of the wavelength in use of the first relaying
node device of the header portion 1101 of the packet by controlling the
section for designation of the wavelength in use of the first relaying
node device as the first section of the input packet A to be not output to
the FIFO I 1207. The packet A output to the FIFO I 1207 is temporarily
stored in the FIFO I, and thereafter, is transmitted from the fixed
wavelength transmitting means I 204 (for transmitting a shorter
wavelength) onto an optical fiber as an optical signal of the wavelength
.lambda.s=.lambda.3. The optical signal is received by the fixed
wavelength receiving means II 205 (for receiving a longer wavelength) of a
node device 105, and is output to the 3.times.3 exchange SW 1201.
In the 3.times.3 exchange SW 1201 of the node device 105, the value in the
section for designation of the wavelength in use of the second relaying
node device as the first section of the header portion 1101 of the input
packet A is read by the latch II 1203, and the read value "1" is output to
the SW control unit 1205. As in the node device 102, the SW control unit
1205 performs arbitration control on the basis of the values output from
the latches I 1202 and III 1204, and the value "1" output from the latch
II 1203, so that packets do not collide in the 3.times.3 SW 1206, and
thereafter, sets the 3.times.3 SW 1206, so that the packet A output from
the fixed wavelength receiving means II 205 is output to the FIFO I 1207.
When the packet is output, the section for designation of the wavelength
in use of the second relaying node device as the first section of the
input packet A is removed.
In this manner, the packet A is temporarily stored in the FIFO I 1207, and
is transmitted from the fixed wavelength transmitting means I 204 (for
transmitting a shorter wavelength) onto the optical fiber as an optical
signal of the wavelength .lambda.s=.lambda.1. The optical signal is
received by the fixed wavelength receiving means I 201 (for receiving a
shorter wavelength) of the node device 109, and is output to the 3.times.3
exchange SW 1201.
In the 3.times.3 exchange SW 1201 of the node device 109, the value in the
first section of the header portion of the packet A is read by the latch I
1202. Since the sections for designation of the wavelength in use of the
first and second relaying node devices of the packet A have already been
removed in the node devices 102 and 105, respectively, the first section
of the header portion of the packet A is the section for identification of
the last relaying node device, and has a value "0". The value "0" in the
section for identification of the last relaying node device is output to
the SW control unit 1205. As in the node devices 102 and 105, the SW
control unit 1205 performs arbitration control on the basis of the values
output from the latches II 1203 and III 1204, and the value "0" output
from the latch I 1202, so that packets do not collide in the 3.times.3 SW
1206, and thereafter, sets the 3.times.3 SW 1206, so that the packet A
output from the fixed wavelength receiving means I 201 is output to the
packet processing unit 208. When the packet A is output, the section for
identification of the last relaying node device as the first section of
the input packet A is removed. In this manner, each of the node devices
102 and 105 for performing the relaying operations removes the first
section of the packet A formed by adding the header portions 1101 that
designates the wavelengths to be used in the respectively relaying node
devices to data in the packet processing unit 208 of the node device 102,
and the packet is supplied to the packet processing unit 208 of the node
device 109. The packet is then subjected to desired processing.
(Second Embodiment)
Table 2 below shows another example of the values in sections for
designation of wavelengths in use of relaying node devices of the first
embodiment of the present invention. As the values in sections for
designation of the wavelengths in use of relaying node devices, "1" to "8"
are assigned in correspondence with transmission wavelengths .lambda.1 to
.lambda.8. FIG. 14 shows an embodiment of the above-mentioned packet A
using Table 2 below. In this embodiment, since the wavelength to be used
is designated by a serial number assigned to each wavelength in place of a
value indicating a shorter or longer wavelength, each node device can
easily change its transmission/reception wavelength.
TABLE 2
______________________________________
Value in Section for
Designation of Wavelength
Wavelength Used by
in Use of Relaying Node
Relaying Node Device
Device
______________________________________
1 1
2 2
3 3
4 4
5 5
6 7
7 8
______________________________________
Value in Section for
Identification of Last
Identification of Last
Relaying Node Relaying Node Device
______________________________________
In Case of Last Relaying
0
Node Device
______________________________________
(Third Embodiment)
FIG. 15 shows the format of a packet according to the third embodiment of
the present invention, which packet is suitably used in the second
multihop system shown in FIGS. 5 and 6.
In the first and second embodiments, since channels (wavelengths) that can
be output from an intermediate relaying node device are predetermined, the
source of a packet must indicate the number of relayings by the number of
sections for designation of wavelengths in use of relaying node devices,
and must designate channels to be used in units of relaying node devices.
However, in the network arrangement of this embodiment, since each relaying
node device has no limitation on channels (wavelengths) to be output, and
can output a packet using a desired channel, the output channels need not
be designated in units of relaying node devices.
Referring to FIG. 15, a section 1501 for indication of the number of
relayings indicates the number of relayings required for transmitting a
packet from a node device as the source to a node device as the
destination. Each relaying node device can recognize based on the value of
the section for indication of the number of relayings whether or not a
node device, which neighbors the own node device at the downstream side in
the transmission direction, is the destination node device. Furthermore,
each node device can recognize whether or not the own node device is the
destination by checking if the value in this section is "0". A section
1502 for designation of the wavelength in use is used for designating the
wavelength to be used in the relaying transmission operation. The section
1501 for indication of the number of relayings and the section 1502 for
designation of the wavelength in use constitute a header portion. As the
value used in the section 1502 for designation of the wavelength in use of
this header portion, "1" to "8" are assigned in correspondence with
transmission wavelengths .lambda.1 to .lambda.8, as shown in Table 3. A
data portion 1102 is carried by this packet.
The arrangement of a node device used in a system using an optical
communication method according to the third embodiment of the present
invention is substantially the same as that of the second multihop system
shown in FIGS. 5A and 5B, except for separation-insertion units I 512 to
VIII 519 and buffers I 520 to VIII 527.
TABLE 3
______________________________________
Value in Section for
Wavelength Used by
Designation of Wavelength
Relaying Node Device
in Use
______________________________________
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
______________________________________
FIG. 16 shows the arrangement of each of the separation-insertion units I
to VIII of the node device suitably used in the system using the optical
communication method of this embodiment. The separation-insertion units I
to VIII have the same internal arrangement.
Referring to FIG. 16, a comparator 1601 checks by comparison if the value
in the section for indication of the number of relayings of a packet
output from a latch 1602 is "0". If the value in the section is "0", the
comparator 1601 outputs a separation instruction to a demultiplexer 1604;
otherwise, it outputs a relaying instruction to the demultiplexer 1604.
The latch 1602 stores the value in the section for indication of the
number of relayings of a packet output from a fixed wavelength reception
unit, and outputs the stored value to the comparator 1601. An I/F unit
1603 outputs a packet output from the demultiplexer 1604 onto a sub
transmission path, and outputs a packet input from the sub transmission
path to a FIFO I 1606. The demultiplexer 1604 outputs an input packet to
the I/F unit 1603 when the comparison result output from the comparator
1601 indicates a separation instruction; or outputs the packet to a FIFO
II 1607 when the comparison result indicates a relaying instruction. An
insertion control unit 1605 controls the reading operations of the FIFOs I
and II, and instructs a selector 1608 of the FIFO to be selected, thereby
inserting a packet transmitted from the sub transmission path into packet
flows output from fixed wavelength reception units 504 to 511. The FIFOs I
1606 and II 1607 temporarily store input packets, and output the stored
packets to the selector in the input order under the control of the
insertion control unit 1605. The selector 1608 selects the FIFO that
stores a packet signal to be output in accordance with an instruction from
the insertion control unit 1605.
FIG. 17 shows the internal arrangement of the buffers I 520 to VIII 527
used in this embodiment. The buffers I to VIII have the same internal
arrangement. Referring to FIG. 17, a demultiplexer 1701 outputs the value
in the section 1502 for designation of the wavelength in use of the header
portion of a packet output from the separation-insertion unit to a latch I
1702, the value in the section 1501 for indication of the number of
relayings to a latch II 1703, and the data portion 1102 to a shift
register 1705. The latch I 1702 stores the value in the section 1502 for
designation of the wavelength in use of the header portion of a packet,
and outputs the stored value to a writing address counter 1706 and a
selector 1707. The latch II 1703 stores the value in the section. 1501 for
indication of the number of relayings of the header portion of the packet,
and outputs the stored value to a down counter 1704. The down counter 1704
decrements the value in the section 1501 for indication of the number of
relayings of the header portion of the packet output from the latch II
1703, and outputs the decremented value to the selector 1707. The shift
register 1705 delays the data portion 1102 of the packet output from the
demultiplexer 1701 by a predetermined period of time, and outputs the
delayed data portion 1102 to the selector 1707. The writing address
counter 1706 generates writing addresses of the packet to be written in a
dual port memory 1709 in accordance with the value in the section 1502 for
designation of the wavelength in use of the header portion of the packet
output from the latch I 1702, and sequentially outputs writing address
signals of the packet to the dual port memory 1709. The selector 1707
re-constructs a packet with the decremented value in the section 1501 for
indication of the number of relayings by sequentially selecting the value
in the section 1502 for designation of the wavelength in use of the header
portion of the packet output from the latch I 1702, the value, decremented
by the down counter 1704, in the section 1501 for indication of the number
of relayings, and the delayed data portion 1102 of the packet output from
the shift register 1705, and outputs the packet to the dual port memory
1709. A reading address counter 1708 sequentially outputs reading address
signals of the packet to the dual port memory 1709 using an offset value
output from a buffer control unit in a control section 501 as the reading
start address. The dual port memory 1709 independently performs the
writing and reading operations of packet data. The memory region of the
dual port memory 1709 is divided into eight regions in correspondence with
the transmission wavelengths of a packet. Memory regions I to VIII
respectively correspond to the transmission wavelengths .lambda.1 to
.lambda.8. The start addresses of these regions are respectively A1, A2,
A3, A4, A5, A6, A7, and A8.
FIG. 18 shows the format of a packet according to this embodiment, whose
source is a terminal equipment I 545 connected to a sub transmission path
I 537 of a node device I 601 and whose destination is a terminal equipment
V 549 connected to a sub transmission path V 541 of a node device IV 604
in the second multihop system shown in FIGS. 5 and 6 using the
above-mentioned node device. Referring to FIG. 18, a value "5" for
designating an optical signal of the wavelength .lambda.5 to be received
by a fixed wavelength reception unit V 508 that outputs a packet to a
separation-insertion unit V 516 to which the sub transmission path 541 as
the destination of the node device IV 604 is connected is set in the
section 1502 for designation of the wavelength in use of the header
portion. In the section 1501 for indication of the number of relayings, a
value "3" indicating the four relaying operations in the own node device I
601, a node device II 602, a node device III 603, and the node device IV
604 is written. In the following description, this packet will be referred
to as a packet B.
The operation of this embodiment will be described below with reference to
FIGS. 16, 17, and 18, and FIGS. 5 and 6. In the following description, the
same constituting elements of different node devices will be denoted by
the same reference numerals in FIGS. 16, 17, and 18, and FIGS. 5 and 6,
for the sake of convenience.
The terminal equipment I 545 as the source, which is connected to the sub
transmission path I 537 of the node device I 601, forms data to be
transmitted to the terminal equipment V 549 connected to the sub
transmission path V 541 of the node device IV 604 as the packet B, as
shown in FIG. 18, and transmits the packet to the separation-insertion
unit I 512 of the node device I 601 via the sub transmission path I 537.
The I/F unit 1603 of the separation-insertion unit I 512 of the node device
I 601 sequentially writes the packet B transmitted through the sub
transmission path I 537 in the FIFO I 1606. Upon completion of the writing
operation of the packet B in the FIFO I 1606, the insertion control unit
1605 detects a division of a packet flow which is being read out from the
FIFO II 1607, switches the FIFO as the input source of the selector 1608
to the FIFO I 1606, stops the reading operation of the FIFO II 1607, and
starts a reading operation of the FIFO I 1606. Thereafter, upon completion
of the reading operation of the packet B written in the FIFO I 1606, the
insertion control unit 1605 switches the FIFO as the input source of the
selector 1608 to the FIFO II 1607 again, stops the reading operation of
the FIFO I 1606, and restarts a reading operation of the FIFO II 1607. The
packet B output from the selector 1608 is input to the buffer I 520.
The demultiplexer 1701 of the buffer I 520 outputs the value in the section
1502 for designation of the wavelength in use of the header portion of the
packet B output from the separation-insertion unit I 512 to the latch I
1702, the value in the section 1501 for indication of the number of
relayings to the latch II 1703, and the data portion 1102 to the shift
register 1705, respectively. The latch I 1702 stores the value in the
section 1501 for indication of the number of relayings, and outputs the
stored value to the down counter 1704. The value in the section 1501 for
indication of the number of relayings of the header portion of the packet
B output from the latch II 1703 is decremented by the down counter 1704,
and the decremented value is output to the selector 1707. The shift
register 1705 delays the data portion 1102 of the packet B output from the
demultiplexer 1701 by a desired period of time, and outputs the delayed
data portion 1102 to the selector 1707. The selector 1707 re-constructs a
packet with the decremented value in the section 1501 for indication of
the number of relayings by sequentially selecting the value in the section
1502 for designation of the wavelength in use of the header portion of the
packet output from the latch I 1702, the value, decremented by the down
counter 1704, in the section 1501 for indication of the number of
relayings, and the delayed data portion 1102 of the packet output from the
shift register 1705, and outputs the packet to the dual port memory 1709.
On the other hand, the writing address counter 1706 sets the writing start
address of the dual port memory 1709 in which the packet B is to be
written to be A5 in correspondence with the value "5" in the section 1502
for designation of the wavelength in use of the header portion of the
packet B output from the latch I 1702, and sequentially outputs writing
address signals of the packet to the dual port memory 1709. The input port
of the dual port memory 1709 receives the re-constructed packet B via the
selector 1707, and the packet B is sequentially written in the memory
region V in accordance with the addresses output from the writing address
counter 1706.
In this manner, after the packet B is written in the memory region V, when
the transmission wavelength of a variable wavelength transmission unit I
528 is set to be .lambda.5 under the control of a wavelength control unit
in the control section 501, a buffer control unit in the control section
501 outputs an offset value A5 corresponding to the memory region V to the
reading address counter 1708 of the buffer I 520. Based on this offset
value A5, the reading address counter 1708 sequentially generates
addresses for reading out the packet B written in the memory region V by
incrementing a counter, and outputs the addresses to the dual port memory
1709. The packet B is sequentially read out from the output port of the
dual port memory 1709 in accordance with the reading addresses, and is
output to the variable wavelength transmission unit I 528. At this time,
since the transmission wavelength of the variable wavelength transmission
unit I 528 is set to be .lambda.5, the packet B is output from the
variable wavelength transmission unit I 528 to a wavelength multiplexer
536 as an optical signal of the wavelength .lambda.5, and the optical
signal is multiplexed with optical signals of different wavelengths output
from other variable wavelength transmission units II 529 to VIII 535. The
multiplexed signal is output onto an optical fiber 502, and is transmitted
to the neighboring node device II 602 at the downstream side.
The packet B transmitted to the node device II 602 as the optical signal of
the wavelength .lambda.5 is subjected to the following relaying
transmission processing in the node device II 602.
Optical signals of the wavelengths .lambda.1 to .lambda.8 transmitted from
the node device I 601 via the optical fiber 502 are divided by a divider
503 in the node device II 602, and the divided signals are respectively
input to fixed wavelength reception units I 504 to VIII 511. The packet B
output from the node device I 601 as the optical signal of the wavelength
.lambda.5 is received by the fixed wavelength reception unit V 508 which
receives only an optical signal of the wavelength .lambda.5. The packet B
received by the fixed wavelength reception unit V 508 is output to the
separation-insertion unit V 516.
The latch 1602 of the separation-insertion unit V 516 stores the value in
the section for indication of the number of relayings of the packet B
output from the fixed wavelength reception unit V 508, and outputs the
stored value to the comparator 1601. Since the value in the section for
indication of the number of relayings of the packet B output from the
latch 1602 is "2", the comparator 1601 outputs a relaying instruction to
the demultiplexer 1604. Upon reception of the relaying instruction from
the comparator 1601, the demultiplexer 1604 outputs the input packet B to
the FIFO II 1607. The packet B written in the FIFO II 1607 is read out
under the control of the insertion control unit 1605, and is output to the
buffer V 524 via the selector 1608.
The value in the section for indication of the number of relayings of the
packet B input to the buffer V 524 is decremented to "1" by the down
counter 1704 as in the buffer I 520 in the node device I 601. Thereafter,
the packet is re-constructed, and is written in the memory region V of the
dual port memory 1709. Thereafter, the packet B is output as an optical
signal of the wavelength .lambda.5 as in the node device I 601, and is
transmitted to the neighboring node device III 603 at the downstream side.
The packet B transmitted to the node device III 603 as the optical signal
of the wavelength .lambda.5 is subjected to the relaying transmission
processing as in the node device II 602, and is then transmitted to the
node device IV 604 as an optical signal of the wavelength .lambda.5. At
this time, the value in the section for indication of the number of
relayings has been decremented to "0".
The packet B transmitted to the node device IV 604 as the optical signal of
the wavelength .lambda.5 is received by the fixed wavelength reception
unit V 508 of the node device IV 604, and is output to the
separation-insertion unit V 516.
The latch device 1602 of the separation-insertion unit V 516 stores the
value in the section for indication of the number of relayings of the
packet B output from the fixed wavelength reception unit V 508, and
outputs the stored value to the comparator 1601. Since the value in the
section for indication of the number of relayings of the packet B output
from the latch 1602 is "0", the comparator 1601 determines that the own
node device is the last relaying node device and the packet is the one to
be relayed to the sub transmission path, and outputs a separation
instruction to the demultiplexer 1604. Upon reception of the separation
instruction from the comparator 1601, the demultiplexer 1604 outputs the
input packet B to the I/F unit 1603. Thus, the packet B is output to the
I/F unit 1603, and is received by the terminal equipment V 549 as the
destination via the sub transmission path V 541. After the header portion
of the packet is removed, only the data portion 1102 is extracted and is
subjected to required processing.
In this manner, the packet B to be transmitted from the terminal equipment
I 545 as the source connected to the sub transmission path I 537 of the
node device I 601 toward the terminal equipment V 549 connected to the sub
transmission path V 541 of the node device IV 604 is output from the
variable wavelength transmission unit I 528 of the node device I 601 as an
optical signal of the wavelength .lambda.5. The packet B is relayed as the
optical signal of the wavelength .lambda.5 while the value in the section
for indication of the number of relayings is decremented in the node
devices I 601, II 602, and III 603. Thereafter, the separation-insertion
unit V 516 of the node device IV 604 detects that the value in the section
for indication of the number of relayings is "0", and the packet B is
separated and transmitted onto the sub transmission path V 541. Then, the
packet B is received by the terminal equipment V 549.
(Fourth Embodiment)
As in the third embodiment, when the output channels of each node device
are not limited like in the above-mentioned second multihop system, the
output channel need only be designated in the node device immediately
before the last node device. As has been exemplified in the third
embodiment, when a packet is to be transmitted from the node device I 601
to the node device IV 604 in FIG. 6, the packet can be input to only the
node device IV 604 as the last relaying node device using the channel
designated by the value in the section 1502 for designation of the
channel. Therefore, at this time, the output channel of the packet in the
node devices I 601 and II 602 is not particularly limited. Such
communication method can be realized in such a manner that the packet can
be stored in any memory region of the dual port memory 1709 when the value
in the section for indication of the number of relayings is other than "1"
in the third embodiment. Alternatively, the following arrangement may be
preferably used.
FIG. 19 shows another internal arrangement of each of the buffers I 520 to
VIII 527 used in the fourth embodiment of the present invention. The
buffers I 520 to VIII 527 have the same internal arrangement.
The same reference numerals in FIG. 19 denote the same blocks as in FIG.
17. Referring to FIG. 19, the down counter 1704 decrements the value in
the section 1501 for indication of the number of relayings of the header
portion of a packet output from the latch II 1703 and outputs the
decremented value to the selector 1707 as in FIG. 17. Also, when the input
value is not "1", the down counter 1704 instructs a demultiplexer II 1901
to set its output destination to be a FIFO III 1902. On the other hand,
when the input value is "1", the down counter 1704 instructs the
demultiplexer II 1901 to set its output destination to be the dual port
memory 1709 since the packet must be input to the fixed wavelength
reception unit, to which the sub transmission path as the destination is
connected, of those of the next node device. The demultiplexer II 1901
outputs the input packet to either the dual port memory 1709 or the FIFO
III 1902 in accordance with the decremented result from the down counter
1704. The FIFO III 1902 temporarily stores the input packet, and outputs
the stored packet to a selector II 1903 in the input order under the
control of a reading control unit. The selector II 1903 selects one of the
outputs from the dual port memory 1709 and the FIFO III 1902 to be output
to the variable wavelength transmission unit in accordance with an
instruction from a buffer control unit.
In the communication method using buffers with this arrangement, after the
transmission wavelength of the variable wavelength transmission unit is
set under the control of a wavelength control unit, a packet which is
written in the dual port memory 1709 and is to be transmitted at the set
wavelength is read out under the control of the buffer control unit, and
thereafter, the contents of the FIFO III 1902 are read out. Thereafter,
the transmission wavelength of the variable wavelength transmission unit
is changed, and the reading operations of the dual port memory 1709 and
the FIFO III 1902 are performed again.
In the above-mentioned arrangement and the communication method, the
above-mentioned packet B is written in the FIFO III 1902 in the buffer I
520 of the node device I 601 since the value in the section 1501 for
indication of the number of relayings of its header portion input to the
down counter 1704 is not "1". Thereafter, the packet B is output from the
variable wavelength transmission unit I 528 as an optical signal of one of
the wavelengths .lambda.1 to .lambda.8. The packet B is received by the
fixed wavelength reception unit, which receives an optical signal of the
transmission wavelength of the packet B, of the eight fixed wavelengths
reception units I 504 to VIII 511 in the node device II 602, and is input
to the buffer via the separation-insertion unit. In the buffer, as in the
node device I 601, since the value in the section 1501 for indication of
the number of relayings of the header portion B input to the down counter
1704 is "2" but not "1", the packet B is written in the FIFO III 1902, and
thereafter, is transmitted from the variable wavelength transmission unit
as an optical signal of one of the wavelengths .lambda.1 to .lambda.8.
Subsequently, in the node device III 603, since the value in the section
1501 for indication of the number of relayings is "1", the packet B is
written in the dual port memory 1709. The memory region in which the
packet B is written at that time is determined by looking up the value in
the section for designation of the wavelength in use of the header portion
of the packet B, and the memory region V is used since the value is "5".
The packet B written in the memory region V is read out under the control
of the buffer control unit, and is output from the variable wavelength
transmission unit V 528 as an optical signal of the wavelength .lambda.5.
Since the separation-insertion unit V 508 of the node device IV 604
detects that the value in the section for indication of the number of
relayings is "0", the packet B is separated and transmitted onto the sub
transmission path V 541 and is received by the terminal equipment V 549.
In the communication method using buffers with the arrangement of this
embodiment, after a packet written in the dual port memory 1709 is
transmitted, a packet written in the FIF0 III 1902 is transmitted without
changing the wavelength. Therefore, the number of times of changing the
wavelength of the variable wavelength transmission unit can be reduced,
and the transmission disable time required for changing the wavelength can
be shortened, thus improving communication efficiency.
In the third and fourth embodiments, since a node device that can transmit
a packet, received at a certain wavelength, at a desired one of all the
wavelengths used in the network is used, even when a certain packet is to
be relayed by a plurality of node devices, only one of the relaying node
devices must relay the packet using the designated wavelength. In this
embodiment, the node device which relays the packet using the designated
wavelength is a node device immediately before the last relaying node
device. However, the present invention is not limited to this. For
example, a node device before the node device immediately before the last
relaying node device may relay the packet using the designated wavelength.
In this case, when the value in the section for indication of the number
of relayings is a predetermined value, the value in the section for
designation of the wavelength in use is looked up, and the packet is
relayed using the designated wavelength. At this time, each of the
subsequent relaying node devices outputs the packet using the same channel
as the input channel. In this embodiment, since the wavelength to be used
is designated in only the relaying operation in one node device, the
header portion of the packet, i.e., the format of the section for
designation of the wavelength in use and the section for indication of the
number of relayings can be simplified.
(Another Embodiment)
In the above and subsequent embodiments, each node device serves as a node
for relaying communications between end terminal equipments or end sub
transmission paths. The sub transmission path may be connected not only to
a terminal equipment but also to another network. The present invention
can be applied not only to a signal input to a node device via a sub
transmission path but also to a communication of a signal generated in the
node device between node devices. In this case as well, when a node device
in which a signal is generated and which starts a communication is
processed as a relaying node device, the present invention can be directly
applied. When the destination of a packet is not a sub transmission path
(or a terminal equipment connected thereto) connected to a node device but
the node device itself, the present invention can be applied if the
destination node device is processed as the last relaying node device.
In the first embodiment, sections for designating the wavelengths to be
used by the respective node devices are used, and the section for
designation of the wavelength in use looked up by the node device that
performs the relaying operation is deleted in each relaying operation. As
another format of the header portion in the first embodiment, a section
for indication of the number of relayings may be allocated at the
beginning of a packet. Other sections are the same as the sections for
designation of the wavelength in use in the first embodiment. A node
device that relays this packet looks up the section for indication of the
number of relayings in the packet, and then looks up the section for
designation of the wavelength in use corresponding to the value in the
former section, thereby determining the transmission wavelength. The
initial value in the section for indication of the number of relayings of
the packet is "1", and the first node device looks up the first section
for designation of the wavelength in use as that corresponding to the
value "1". Thereafter, the node device processes this packet to increment
the value in the section for indication of the number of relayings to "2",
and outputs the processed packet onto the transmission path. The next
relaying node device looks up the second section for designation of the
wavelength in use since the value in the section for indication of the
number of relayings is "2". Thereafter, the node device increments the
value in the section for indication of the number of relayings to "3", and
outputs the packet onto the transmission path. Each node device increments
the value in the section for indication of the number of relayings in each
relaying operation. With this format, the looked-up section for
designation of the wavelength in use need not be deleted in each relaying
operation unlike in the first embodiment.
More specifically, according to the present invention, a packet has a
format with which each relaying node device can recognize whether or not
the wavelength to be used in the relaying operation is designated or which
transmission wavelength it must use when the wavelength is designated,
without looking up all the addresses. For this reason, the relaying node
device can look up only a portion to be looked up by the own node device
of the address portion in the packet only when the own node device is
required to look it up. Furthermore, when a packet is relayed by a
plurality of node devices, each relaying node device need only have means
for allowing a subsequent node device or devices, which must relay the
packet by looking up the sections for designation of the wavelength in
use, to look up a portion to be looked up (e.g., by removing the section
looked up by the own node device or performing a calculation for the
section for indication of the number of relayings).
In the above and subsequent embodiments, a plurality of channels are
constituted using different wavelengths. However, the present invention is
not limited to this, but is effective to a case wherein a destination
terminal equipment or the like is connected to only some channels in a
network having a plurality of transmission channels. More specifically, as
transmission channels, in place of the wavelength multiplex channels in
the above-mentioned embodiments, various kinds of channels such as
frequency multiplex channels using electrical signals, spatial multiplex
channels obtained by bundling a plurality of transmission paths, and the
like may be used. Note that term "multiplex" here means a theoretical one,
and a plurality of channels need not be physically multiplexed in a single
transmission path or a plurality of transmission paths need not be
physically bundled. For example, a plurality of channels may be obtained
by the wavelength multiplex method using space as a transmission path.
In the third and fourth embodiments, the section for indication of the
number of relayings is allocated in the packet to indicate the number of
relayings. Alternatively, the system of each of the third and fourth
embodiments may adopt an arrangement using the packet used in the first
embodiment. In this case, however, since the channels of node devices
other than a node device immediately before the destination node device
need not be designated, significant values need not be set in sections for
designation of the wavelength in use of relaying node devices other than
that of the node device immediately before the last relaying node device
(destination node device). The number of sections for designation of the
wavelength in use of relaying node devices set in a packet serves as
information indicating the number of relayings.
As described above, according to the node device for the channel multiplex
network system and the communication method of the present invention,
since the channel of a signal used in the relaying operation is determined
based on each of or a combination of information indicating whether or not
an output channel must be designated in the relaying operation,
information indicating the output channel, information indicating the
number of relayings, and the like, without comparing the destination
address with those of all the terminal equipments connected to the network
system, decoders in the node device can be simplified or omitted, and the
channel to be used in the relaying operation can be determined at high
speed. For this reason, a low-cost node device which can prevent an
increase in its hardware scale can be provided, and a high-speed operation
of the network system can be assured.
Since the sections for designating channels of a signal to be used in the
relaying operations are assigned in units of relaying node devices, each
relaying node device performs the relaying operation by, e.g., deleting
the section assigned to the own node device. For this reason, since the
relaying node device need only process the section for designating a
channel of a signal to be used in the own node device, which section is
located at the beginning of the header portion, simple, high-speed
processing can be assured.
Furthermore, when the header portion includes a section for indicating the
number of relayings and a section for designating the channel of a signal
to be used in the relaying operation, if the number of relayings is large,
the header portion can be shortened as compared to a case wherein the
channels to be used by the respective node devices are individually
designated, thus improving the communication efficiency.
Moreover, when the header portion is assigned a function of instructing not
to designate the channel to be used in the relaying operation, the change
interval of the transmission wavelength can be prolonged, and the
transmission disable time required for changing the wavelength can be
shortened, thus improving the communication efficiency.
(Fifth Embodiment)
In the arrangement of each of the third and fourth embodiments, when a
terminal equipment wants to broadcast a packet to all the terminal
equipments connected to the network system, it looks up a terminal
equipment connection table to obtain information associated with the
numbers of relayings to the respective terminal equipments and the
channels to which the respective terminals are connected, forms a packet
using the obtained information as address information, and transmits the
packet toward the respective terminal equipments, thereby broadcasting the
packet.
In this embodiment and the sixth embodiment to be described later, the
broadcasting method is improved, and a packet can be broadcasted without
looking up the terminal equipment connection table.
FIG. 20 shows the format of a broadcasting packet suitably used in this
embodiment.
Referring to FIG. 20, a section 2001 for indication of the number of
relayings indicates the number of relayings required for transmitting a
packet from the source node device of the broadcasting packet to the
destination node device. Each relaying node device can recognize whether
or not the neighboring node device at the downstream side in the
transmission direction is the destination node device by checking if the
value in the section 2001 for indication of the number of relayings is
"1". Also, by checking if this value is "0", each node device can
recognize whether or not a terminal device connected to itself is the
destination. A section 2002 for designation of the wavelength in use
designates the wavelength to be used in the relaying transmission
operation. As the value to be used in the section 2002 for designation of
the wavelength in use of this header portion, "1" to "8" are respectively
assigned in correspondence with transmission wavelengths .lambda.1 to
.lambda.8, as shown in Table 2 above. A section 2003 for identification of
the kind of packet indicates the kind of this packet, and a value
indicating a broadcasting packet is set as the type of packet. The header
portion also includes a remaining header portion 2004. The section 2001
for indication of the number of relayings, the section 2002 for
designation of the wavelength in use, the section 2003 for identification
of the kind of packet, and the remaining header portion 2004 constitute
the header portion. A section 2005 for identification of the broadcasting
terminal equipment is written with the terminal equipment identification
number of the broadcasting terminal equipment as the source of a
broadcasting packet. Data to be broadcasted is written in a data portion
2006.
FIG. 21 is a flow chart showing the operation of the broadcasting terminal
equipment as the source of a broadcasting packet in this embodiment.
A case will be exemplified below wherein the terminal equipment I 545
connected to the node device I 601 broadcasts data in the arrangement of
the network system shown in FIG. 6 using the arrangement of the node
device shown in FIGS. 5A and 5B. In the following description, the same
constituting elements in different terminal equipments are denoted by the
same reference numerals as in FIGS. 5A, 5B, 6, 9, 16, and 17, for the sake
of convenience.
The terminal equipment I 545 as the broadcasting terminal equipment
connected to the node device I 601 forms a broadcasting packet by setting
"1" in the section 2001 for indication of the number of relayings and "1"
in the section 2002 for designation of the wavelength in use, and
transmits the packet to the separation-insertion unit I 512 of the node
device I 601 via the sub transmission path I 537. At this time, the
identification number of the terminal equipment I 545 is written in the
section for identification of the broadcasting terminal equipment of the
broadcasting packet. In the following description, this packet will be
referred to as a packet C.
The I/F unit 1603 of the separation-insertion unit I 512 of the node device
I 601 sequentially writes the broadcasting packet C transmitted via the
sub transmission path I 537 in the FIFO I 1606. Upon completion of the
writing operation of the broadcasting packet C in the FIFO I 1606, the
insertion control unit 1605 detects a division of a packet flow which is
being read out from the FIFO II 1607, switches the input source of the
selector 1608 to the FIFO I 1606, stops the reading operation of the FIFO
II 1607, and starts a reading operation of the FIFO I 1606. Thereafter,
upon completion of the reading operation of the broadcasting packet C
written in the FIFO I 1606, the insertion control unit 1605 switches the
input source of the selector 1608 to the FIFO II 1607 again, stops the
reading operation of the FIFO I 1606, and restarts a reading operation of
the FIFO II 1607. The broadcasting packet C output from the selector 1608
is input to the buffer I 520.
The demultiplexer 1701 of the buffer I 520 outputs the value in the section
2002 for designation of the wavelength in use of the header portion of the
broadcasting packet C output from the separation-insertion unit to the
latch I 1702, the value in the section 2001 for indication of the number
of relayings to the latch II 1703, and the data portion 2006 to the shift
register 1705, respectively. The latch I 1702 stores the value in the
section 2002 for designation of the wavelength in use of the header
portion of the broadcasting packet C, and outputs the stored value to the
writing address counter 1706 and the selector 1707. The latch II 1703
stores the value in the section 2001 for indication of the number of
relayings of the header portion of the broadcasting packet C, and outputs
the stored value to the down counter 1704. The value "1" in the section
2001 for indication of the number of relayings of the header portion of
the broadcasting packet C output from the latch II 1703 is decremented to
"0" by the down counter 1704, and the value "0" is output to the selector
1707. The shift register 1705 delays the data portion 2006 of the
broadcasting packet C output from the demultiplexer 1701 by a desired
period of time, and outputs the delayed data portion 2006 to the selector
1707. The selector 1707 re-constructs the broadcasting packet B with the
decremented value in the section 2001 for indication of the number of
relayings by sequentially selecting the value in the section 2002 for
designation of the wavelength in use of the header portion of the packet C
output from the latch I 1702, the value in the section 2002 for indication
of the number of relayings decremented by the down counter 1704, and the
delayed data portion 2006 of the broadcasting packet C output from the
shift register 1705. The selector 1707 then outputs the packet to the dual
port memory 1709.
On the other hand, the writing address counter 1706 sets the writing start
address of the dual port memory 1709, in which the broadcasting packet C
is to be written, to be A1 in accordance with the value "1" in the section
2002 for designation of the wavelength in use of the header portion of the
broadcasting packet C output from the latch I 1702, and sequentially
outputs writing address signals of the packet to the dual port memory
1709. The input port of the dual port memory 1709 receives the
re-constructed broadcasting packet C via the selector 1707, and the packet
C is sequentially written in the memory region I in accordance with the
addresses output from the writing address counter 1706. After the
broadcasting packet C is written in the memory region I in this manner,
when the transmission wavelength of the variable wavelength transmission
unit I 528 is set to be .lambda.1 under the control of the wavelength
control unit in the control section 501, the buffer control unit in the
control section 501 outputs an offset value A1 corresponding to the memory
region I to the reading address counter 1708 of the buffer I 520. Based on
this offset value A1, the reading address counter 1708 generates addresses
for reading out the broadcasting packet C written in the memory region I
by sequentially incrementing a counter, and outputs the addresses to the
dual port memory 1709. The broadcasting packet C is sequentially read out
from the output port of the dual port memory 1709 on the basis of the
reading addresses, and is output to the variable wavelength transmission
unit I 528. Since the transmission wavelength of the variable wavelength
transmission unit I 528 is set to be .lambda.1, the broadcasting packet C
is output from the variable wavelength transmission unit I 528 to the
wavelength multiplexer 536 as an optical signal of the wavelength
.lambda.1, and is multiplexed with optical signals of different
wavelengths output from other variable wavelength transmission units II
529 to VIII 535 by the wavelength multiplexer 536. Then, the multiplexed
signal is output onto the optical fiber 502 and is transmitted to the
neighboring node device II 602 at the downstream side.
The broadcasting packet C transmitted to the node device II 602 as the
optical signal of the wavelength .lambda.1 is received by the fixed
wavelength reception unit I 504 of the node device II 602, and is output
to the separation-insertion unit I 512. The latch 1602 of the
separation-insertion unit I 512 stores the value in the section 2001 for
indication of the number of relayings of the broadcasting packet C output
from the fixed wavelength reception unit I 504, and outputs the stored
value to the comparator 1601. Since the value in the section 2001 for
indication of the number of relayings of the broadcasting packet C output
from the latch 1602 is "0", the comparator 1601 outputs a separation
instruction to the demultiplexer 1604. Upon reception of the separation
instruction from the comparator 1601, the demultiplexer 1604 outputs the
input broadcasting packet C to the I/F unit 1603. Thus, the broadcasting
packet C is output to the I/F unit 1603, and is transmitted onto the sub
transmission path I 537. Thereafter, the packet C is received by the
terminal equipment I 545 as the destination. The packet processing unit
902 reads the value in the section 2003 for identification of the kind of
packet of the header portion and performs predetermined reception
processing of the packet since the value indicating the broadcasting
packet is set in the section 2003.
After the first broadcasting packet C is transmitted, the terminal
equipment I 545 as the broadcasting terminal equipment connected to the
node device I 601 forms seven broadcasting packets by setting "1" in their
sections 2001 for indication of the number of relayings, and setting "2"
to "8" in their sections 2002 for designation of the wavelength in use,
and transmits these packets to the separation-insertion unit I 512 of the
node device I 601 via the sub transmission path I 537 as in the
above-mentioned broadcasting packet C.
At this time, the values in the sections 2005 for identification of the
broadcasting terminal equipment of these seven broadcasting packets are
the same as that in the broadcasting packet C. These seven broadcasting
packets are respectively processed in the same manner as the broadcasting
packet C and are output from the separation-insertion unit I 512 to the
buffer I 520. In the buffer I 520, the values "1" in the sections 2001 for
indication of the number of relayings in these seven broadcasting packets
are decremented to "0" by the down counter 1704, and the seven
broadcasting packets are respectively written in the memory regions II to
VIII of the dual port memory in accordance with the values in the sections
2002 for designation of the wavelength in use of their header portions.
After the seven broadcasting packets are written in the memory regions II
to VIII in this manner, these packets are transmitted from the variable
wavelength transmission unit I 528 to the neighboring node device II 602
at predetermined wavelengths set in their sections 2002 for designation of
the wavelength in use under the control of the wavelength control unit and
the buffer control unit in the control section 501.
The seven broadcasting packets transmitted to the node device II 602 are
respectively received by the fixed wavelength reception units II 505 to
VIII 5111 of the node device II 602 in accordance with the wavelengths set
in their sections 2002 for designation of the wavelength in use, and are
separated by the separation-insertion units II 513 to VIII 519 as in the
broadcasting packet C. Then, the seven broadcasting packets are
respectively output to the terminal equipments II 546 to VIII 552 via the
corresponding sub transmission paths. In the terminal equipments II 546 to
VIII 552, the packets are subjected to reception processing in the same
manner as the broadcasting packet C.
In this manner, the broadcasting packets are transmitted from the terminal
equipment I 545 connected to the node device I 601 to the terminal
equipments I 545 to VIII 552 connected to the node device II 601 and are
subjected to reception processing.
Subsequently, the terminal equipment I 545 as the broadcasting terminal
equipment connected to the node device I 601 forms eight broadcasting
packets by setting "2" in their sections 2001 for indication of the number
of relayings, and setting "1" to "8" in their sections 2002 for
designation of the wavelength in use, and transmits these packets. At this
time, the values in the sections 2005 for identification of the
broadcasting terminal equipment of these eight broadcasting packets are
the same as that in the above-mentioned broadcasting packet C. These eight
broadcasting packets are processed by the node device I 601 in the same
manner as in the broadcasting packet C, and the values in their sections
2001 for indication of the number of relayings are decremented from "2" to
"1". Thereafter, these packets are output to the node device II 602. In
the separation-insertion unit of the node device II 602, since the values
in the sections 2001 for indication of the number of relayings are "1",
the input packets are not separated but are output to the buffers. After
the values in the sections 2001 for indication of the number of relayings
are decremented from "1" to "0", the packets are output from the variable
wavelength transmission unit to the node device III 603. Since the values
in the sections 2001 for indication of the number of relayings are "0",
these packets are separated in the node device III 603, and are
respectively output to the terminal equipments I 545 to VIII 552.
Thereafter, the packets are subjected to the processing in the same manner
as described above. In this manner, the broadcasting packets are
transmitted to the terminal equipments I 545 to VIII 552 connected to the
node device III 603 and are subjected to reception processing.
Subsequently, the terminal equipment I 545 as the broadcasting terminal
equipment connected to the node device I 601 similarly forms eight
broadcasting packets by setting "3" in their sections 2001 for indication
of the number of relayings, and transmits these packets.
These eight broadcasting packets are relayed by the node devices II 602 and
III 603 in the same manner as described above, and are separated from
packet flows of the respective channels by the eight separation-insertion
units of the node device IV 604. The separated packets are transmitted to
the terminal equipments I 545 to VIII 552 connected to the node device IV
604 and are then subjected to reception processing.
Furthermore, the terminal equipment I 545 as the broadcasting terminal
equipment connected to the node device I 601 similarly forms eight
broadcasting packets by setting "4" in their sections 2001 for indication
of the number of relayings, and transmits these packets. These eight
broadcasting packets are relayed by the node devices II 602, III 603, and
IV 604 in the same manner as described above, and are received by the
eight terminal equipments connected to the node device I 601. At this
time, the terminal equipments II 546 to VIII 552 connected to the node
device I 601 perform the reception processing of the broadcasting packets.
On the other hand, the terminal equipment I 545 connected to the node
device I 601 is the broadcasting terminal equipment that transmitted the
broadcasting packets. The broadcasting terminal equipment detects based on
the value in the section 2005 for identification of the broadcasting
terminal equipment in the received broadcasting packet that this
broadcasting packet was transmitted from the own terminal equipment, was
relayed by all the node devices on the network system, and returned to the
own terminal equipment after it traveled through the network once, thus
ending transmission of the broadcasting packets.
In this embodiment, since all the node devices can receive all the
wavelengths and have a function of transmitting a received packet using a
desired wavelength as in the third and fourth embodiments, the
transmission wavelength of only one of the relaying node devices of a
broadcasting packet need be designated.
(Sixth Embodiment)
FIG. 22 shows the second embodiment of a broadcasting packet according to
the present invention. Referring to FIG. 22, a section 2007 for
designation of the relaying terminal equipment designates the terminal
equipment, which must relay and transmit a received broadcasting packet,
of the eight terminal equipments connected to the node device. The
designation is attained by designating the wavelength (to be referred to
as a reception wavelength hereinafter) which is received by the fixed
wavelength reception unit that outputs a packet to the
separation-insertion unit to which the terminal equipment is connected via
the sub transmission path, and the terminal equipment which received the
packet of the designated wavelength relays and transmits the broadcasting
packet.
FIG. 23 is a flow chart showing the operation of the terminal equipment as
the source of a broadcasting packet in this embodiment.
FIG. 24 is a flow chart showing the operation of the terminal equipment
which receives the broadcasting packet in this embodiment.
In this embodiment, the terminal equipment as the source of a broadcasting
packet sequentially outputs eight packets in which "1" is set in the
sections 2001 for indication of the number of relayings, and "1" to "8"
are set in the sections 2002 for designation of the wavelength in use, and
transmits the broadcasting packets to only the terminal equipments
connected to the neighboring node device at the downstream side. The
terminal equipments which received these broadcasting packets perform the
reception processing of the broadcasting packets as in the fifth
embodiment. Furthermore, the terminal equipment designated by the value in
the section 2007 for designation of the relaying terminal equipment
transmits eight packets, in which "1" is set in the sections 2001 for
indication of the number of relayings, and "1" to "8" are set in the
sections 2002 for designation of the wavelength in use, to only the eight
terminal equipments connected to the neighboring node device at the
downstream side. In this manner, the broadcasting packets are sequentially
transmitted from the terminal equipment designated by the value in the
section for designation of the relaying terminal equipment in the
broadcasting packet to the terminal equipments connected to the
neighboring node device at the downstream side. When the terminal
equipment as the source of the broadcasting packet receives this
broadcasting packet, the transmission of the broadcasting packet ends.
In this embodiment, since the number of broadcasting packets to be
transmitted from the terminal equipment as the source of the broadcasting
packet can become small, and the broadcasting packets are transmitted from
a plurality of terminal equipments, the load upon transmission of the
broadcasting packet can be reduced.
In the fifth embodiment, after the value in the section for designation of
the wavelength in use is changed from "1" to "8" while the number of
relayings is fixed, whether or not the broadcasting operation is to be
ended is determined by checking if the broadcasting packet transmitted
from the own terminal equipment is received, before the number of
relayings is increased. However, the present invention is not limited to
this. For example, the broadcasting operation may be ended as soon as it
is detected that the received packet is the broadcasting packet
transmitted from the own terminal equipment. However, in this arrangement,
if the packet transmitted from the own terminal equipment is received
before the broadcasting packet to be transmitted is broadcasted to all the
terminal equipments (such an error tends to occur especially when the
number of nodes or the number of wavelengths is small), transmission of
the broadcasting packet undesirably ends at that time, and the
broadcasting packet can no longer be transmitted even if more destinations
to which the broadcasting packet need be transmitted still remain (in
particular, other destinations connected to the node device to which the
broadcasting source is connected). In order to solve this problem, a
packet to be transmitted from the source to the respective node devices
using a wavelength that can be received by the own terminal equipment
(.lambda.1 in the fifth embodiment) is sent after packets transmitted
using other wavelengths. For example, in the fifth embodiment, when
packets in which the value in the section for designation of the
wavelength in use is sequentially changed while the value in the section
for indication of the number of relayings is fixed are output from the
source terminal equipment, the value to be set in the section for
designation of the wavelength in use can be changed in the order of, e.g.,
2.fwdarw.3.fwdarw.4.fwdarw.5.fwdarw.6 .fwdarw.7.fwdarw.8.fwdarw.1, so that
"1" indicating the wavelength that can be received by the source is set
last.
The same applies to the sixth embodiment. However, in the sixth embodiment,
if there are two or more node devices, the source receives a packet
relayed by another terminal equipment (not limited to the terminal
equipment as long as a means can process and transmit a packet) as a
packet broadcasted by the own source, the wavelength that can be received
by the source must be designated for the relaying terminal equipment.
Alternatively, the need for this designation can be obviated if terminal
equipments that can receive the same wavelength as reception wavelength of
the broadcasting source are used as relaying terminal equipments.
As described above, in the packet broadcasting method of the fifth and
sixth embodiments, since a broadcasting packet can be transmitted to all
the terminal equipments via the network system without looking up the
terminal equipment connection table, a packet can be broadcasted even when
none of the terminal equipments have a terminal equipment connection table
(e.g., when a new network system is constituted or when the arrangement of
the network system is changed).
The terminal equipment as the source can detect that the broadcasting
packet was transmitted to all the terminal equipments since the
broadcasting packet transmitted from the own terminal equipment is sent
back to the own terminal equipment. For this reason, each terminal
equipment which received the broadcasting packet need not send back a
reception response packet, and completion of transmission of the
broadcasting packet to all the terminal equipments can be easily detected.
A packet can be broadcasted from a terminal equipment, which is not
registered in the terminal equipment connection tables of other terminal
equipments on the network system (such as a new terminal equipment added
to the network system or a terminal equipment whose connection
relationship is changed). Also, a packet can be broadcasted even when the
network system includes a terminal equipment whose terminal equipment
connection table suffers an error.
(Seventh Embodiment)
FIG. 25 shows the format of a packet for count of the number of node
devices according to the seventh embodiment of the present invention,
which packet is suitably used in a terminal equipment connection table
generation method in the above-mentioned multihop system. The packet for
count of the number of node devices is transmitted from a terminal
equipment (to be referred to as a server hereinafter) which generates a
terminal equipment connection table when a new network system is
constituted or when the arrangement of the network system is changed, and
is used for counting the number of node devices connected to the network
system. The number of node devices obtained using this packet is used for
calculating the values in sections for indication of the number of
relayings in the terminal equipment connection table, as will be described
later.
Referring to FIG. 25, a section 2501 for indication of the number of
relayings indicates the number of relayings required for transmitting a
packet from a node device as the source to a node device as the
destination. Each node device can recognize based on the value in the
section for indication of the number of relayings in the relaying
operation whether or not the neighboring node device at the downstream
side in the transmission direction is a node device as the destination.
Also, each node device can determine whether or not a terminal equipment
connected to the own node device is the destination by checking if the
value in this section is "0". A section 2502 for designation of the
wavelength in use designates the wavelength to be used in the relaying
transmission operation. As the value to be used in the section 2502 for
designation of the wavelength in use, "1" to "8" are assigned in
correspondence with transmission wavelengths .lambda.1 to .lambda.8, as
shown in Table 2 above. A section 2503 for identification of the kind of
packet indicates the kind of packet, and a value indicating the packet for
count of the number of node devices is set as the kind of packet. The
header portion also includes a remaining header portion 2504. The section
2501 for indication of the number of relayings, the section 2502 for
designation of the wavelength in use, the section 2503 for identification
of the kind of packet, and the remaining header portion 2504 constitute
the header portion.
A section 2505 for the initial setting value in the section of indication
of the number of relayings is written with a value, which is set in the
section for indication of the number of relayings by the source terminal
equipment of the packet for count of the number of node devices. The
packet also has a remaining data portion 2506. The value in the section
2505 for the initial setting value in the section of indication of the
number of relayings and the remaining data portion 2506 constitute a data
portion to be carried by this packet.
FIG. 26 shows the format of a packet for notification of the number of
nodes according to the present invention. The packet for notification of
the number of nodes is transmitted from the server to notify all the
terminal equipments on the network system of the number of node devices
after the server obtains the number of node devices connected to the
network system using the packet for count of the number of node devices.
Referring to FIG. 26, a section 2601 for the reception wavelength of the
server stores a value indicating the reception wavelength of the server. A
section 2602 for identification of the server stores a value indicating
the identification number of the server. A section 2603 for the number of
all relaying node devices stores a value indicating the number of all the
relaying node devices obtained by using the packet for count of the number
of node devices. In the packet for notification of the number of node
devices, a value indicating the packet for notification of the number of
node devices as the kind of packet is set in the section for
identification of the kind of packet.
FIG. 27 shows the format of a packet for report of the connection form
according to the present invention. The packet for report of the
connection form is transmitted from a terminal equipment which received
the packet for notification of the number of node devices transmitted from
the server so as to report the connection information and identification
number of the own terminal equipment to the server. Referring to FIG. 27,
a section 2701 for the reception wavelength of the terminal equipment
stores a value indicating the reception wavelength of the terminal
equipment. A section 2702 for identification of the terminal equipment
stores a value indicating the identification number of the terminal
equipment. In the packet for report of the connection form, a value
indicating the packet for report of the connection form as the kind of
packet is set in the section for identification of the kind of packet.
The first embodiment of a terminal equipment connection table generation
method according to the present invention using the packet for count of
the number of node devices, the packet for notification of the number of
node devices, and the packet for report of the connection form described
above will be described below with reference to the operation flow charts
shown in FIGS. 28 and 29. In the following description, a case will be
exemplified below wherein the terminal equipment I 545 connected to the
node device I 601 serves as a server when a network system having the
arrangement shown in FIG. 6 using the arrangement of the node device shown
in FIGS. 5A and 5B is newly constituted.
FIG. 28 is a flow chart showing the operation of the server as the source
terminal equipment of the packet for count of the number of node devices
in the seventh embodiment of the present invention, and FIG. 29 is a flow
chart showing the operation of the sever as the source terminal equipment
of the packet for notification of the number of node devices in the
seventh embodiment of the present invention. In the following description,
the same constituting elements in different terminal equipments are
denoted by the same reference numerals as in FIGS. 5A, 5B, 6, 9, 16, and
17, for the sake of convenience. In the arrangement of the network system
shown in FIGS. 5A and 5B, assume that identification numbers "11" to "18"
are respectively assigned to the terminal equipments I 545 to VIII 552
connected to the node device I 601, identification numbers "21" to "28"
are respectively assigned to the terminal equipments I 545 to VIII 552
connected to the node device II 602, identification numbers "31" to "38"
are respectively assigned to the terminal equipments I 545 to VIII 552
connected to the node device III 603, and identification numbers "41" to
"48" are respectively assigned to the terminal equipments I 545 to VIII
552 connected to the node device IV 604.
In the process of transmitting the packet for count of the number of node
devices, which is used for detecting the number of node devices connected
to the network system, the terminal equipment I 545 as the server
connected to the node device I 601 forms a packet for count of the number
of node devices by setting "1" in the section 2501 for indication of the
number of relayings of the header portion, "1" in the section 2502 for
designation of the wavelength in use, "1" in the section 2505 for the
initial setting value in the section for indication of the number of
relayings, and a predetermined value in the section 2503 for
identification of the kind of packet, and transmits this packet to the
separation-insertion unit I 512 of the node device I 601 via the sub
transmission path I 537. In the following description, this packet will be
referred to as a packet D for count of the number of node devices.
The I/F unit 1603 of the separation-insertion unit I 512 of the node device
I 601 sequentially writes the packet D for count of the number of node
devices transmitted via the sub transmission path 537 in the FIFO I 1606.
Upon completion of the writing operation of the packet D for count of the
number of node devices in the FIFO I 1606, the insertion control unit 1605
detects a division of a packet flow which is being read out from the FIFO
II 1607, switches the input source of the selector 1608 to the FIFO I
1606, stops the reading operation of the FIFO II 1607, and starts a
reading operation of the FIFO I 1606. Thereafter, upon completion of the
reading operation of the packet D for count of the number of node devices
written in the FIFO I 1606, the insertion control unit 1605 switches the
input source of the selector 1608 to the FIFO II 1607 again, stops the
reading operation of the FIFO I 1606, and restarts a reading operation of
the FIFO II 1607. The packet D for count of the number of node devices
output from the selector 1608 is input to the buffer I 520.
The demultiplexer 1701 of the buffer I 520 outputs the value in the section
2502 for designation of the wavelength in use of the header portion of the
packet D for count of the number of node devices output from the
separation-insertion unit 512 to the latch I 1702, the value in the
section 2501 for indication of the number of relayings to the latch II
1703, and the data portion to the shift register 1705. The latch I 1702
stores the value in the section 2502 for designation of the wavelength in
use of the header portion of the packet D for count of the number of node
devices, and outputs the stored value to the writing address counter 1706
and the selector 1707. The latch II 1703 stores the value in the section
2501 for indication of the number of relayings of the header portion of
the packet D for count of the number of node devices, and outputs the
stored value to the down counter 1704. The value "1" in the section 2501
for indication of the number of relayings of the header portion of the
packet D for count of the number of node devices output from the latch II
1703 is decremented to "0" by the down counter 1704, and the decremented
value is output to the selector 1707. The shift register 1705 delays the
data portion of the packet D for count of the number of node devices
output from the demultiplexer 1701 by a desired period of time, and
outputs the delayed data portion to the selector 1707. The selector 1707
re-constructs the packet D for count of the number of node devices by
sequentially selecting the value in the section 2502 for designation of
the wavelength in use of the header portion of the packet D for count of
the number of node devices output from the latch I 1702, the value in the
section 2501 for indication of the number of relayings decremented by the
down counter 1704, and the delayed data portion of the packet D for count
of the number of node devices output from the shift register 1705. Then,
the selector 1707 outputs the re-constructed packet to the dual port
memory 1709. On the other hand, the writing address counter 1706 sets the
writing start address of the dual port memory 1709, in which the packet D
for count of the number of node devices is to be written, to be A1 in
accordance with the value "1" in the section 2502 for designation of the
wavelength in use of the header portion of the packet D for count of the
number of node devices output from the latch I 1702, and sequentially
outputs writing address signals of the packet to the dual port memory
1709. The input port of the dual port memory 1709 receives the
re-constructed packet D for count of the number of node devices via the
selector 1707, and the packet D is sequentially written in the memory
region I in accordance with the addresses output from the writing address
counter 1706.
After the packet D for count of the number of node devices is written in
the memory region I, when the transmission wavelength of the variable
wavelength transmission unit I 528 is set to be .lambda.1 under the
control of the wavelength control unit in the control section 501, the
buffer control unit in the control section 501 outputs an offset value A1
corresponding to the memory region I to the reading address counter 1708
of the buffer I 520. Based on this offset value A1, the reading address
counter 1708 generates addresses for reading out the packet D for count of
the number of node devices written in the memory region I by sequentially
incrementing a counter, and outputs the addresses to the dual port memory
1709. The packet D for count of the number of node devices is read out
from the output port of the dual port memory 1709 in accordance with the
reading addresses, and is output to the variable wavelength transmission
unit I 528. Since the transmission wavelength of the variable wavelength
transmission unit I 528 is set to be .lambda.1, the packet D for count of
the number of node devices is output from the variable wavelength
transmission unit I 528 to the wavelength multiplexer 536 as an optical
signal of the wavelength .lambda.1. The wavelength multiplexer 536
multiplexes the packet D with optical signals of different wavelengths
output from other variable wavelength transmission units II 529 to VIII
535, and outputs the multiplexed signal onto the optical fiber 502. The
optical signal is transmitted to the neighboring node device II 602 at the
downstream side.
The packet D for count of the number of node devices transmitted to the
node device II 602 as the optical signal of the wavelength .lambda.1 is
received by the fixed wavelength reception unit I 504 of the node device
II 602, and is output to the separation-insertion unit I 512. The latch
1602 of the separation-insertion unit I 512 stores the value in the
section 2501 for indication of the number of relayings of the packet D for
count of the number of node devices output from the fixed wavelength
reception unit I 504, and outputs the stored value to the comparator 1601.
Since the value in the section 2501 for indication of the number of
relayings of the packet D for count of the number of node devices output
from the latch 1602 is "0", the comparator 1601 outputs a separation
instruction to the demultiplexer 1604. Upon reception of the separation
instruction from the comparator 1601, the demultiplexer 1604 outputs the
input packet D for count of the number of node devices to the I/F unit
1603. Thus, the packet D for count of the number of node devices is output
to the I/F unit 1603, and is then output onto the sub transmission path I
537. Thereafter, the packet D is received by the terminal equipment I 545
as the destination. The value in the section 2503 for identification of
the kind of packet of the header portion is read by the packet processing
unit 902. Since the section 2503 for identification of the kind of packet
stores the value indicating the packet for count of the number of node
devices, this packet is abandoned without any processing.
After the packet D for count of the number of node devices is transmitted,
the terminal equipment I 545 as the server connected to the node device I
601 forms a packet for count of the number of node devices in which "2" is
set in the section 2501 for indication of the number of relayings and the
section 2505 for the initial setting value in the section for indication
of the number of relayings in the header portion, and the same values as
in the packet D for count of the number of node devices are set in other
sections, and transmits this packet.
This packet for count of the number of node devices is processed by the
node device I 601 in the same manner as the packet D for count of the
number of node devices, and the value in the section 2501 for indication
of the number of relayings is decremented from "2" to "1". Then, the
packet is output to the node device II 602. Since the value in the section
2501 for indication of the number of relayings is "1", the
separation-insertion unit of the node device II 602 does not separate the
packet but outputs it to the buffer, and the value in the section 2501 for
indication of the number of relayings is decremented from "1" to "0".
Thereafter, the packet is output from the variable wavelength transmission
unit to the node device III 603. Since the value in the section 2501 for
indication of the number of relayings is "0", the node device III 603
separates this packet and outputs the packet to the terminal I 545.
Thereafter, the packet is abandoned in the packet processing unit 902 in
the same manner as described above.
Subsequently, the terminal equipment I 545 as the server connected to the
node device I 601 forms a packet for count of the number of node devices
in which "3" is set in the section 2501 for indication of the number of
relayings and the section 2505 for the initial setting value in the
section for indication of the number of relayings in the header portion,
and transmits this packet. This packet for count of the number of node
devices is similarly relayed by the node devices II 602 and III 603, is
received by the terminal equipment I 545 connected to the node device IV
604, and thereafter, is abandoned by the packet processing unit 902 in the
same manner as described above.
Furthermore, the terminal equipment I 545 as the server connected to the
node device I 601 forms a packet for count of the number of node devices
in which "4" is set in the section 2501 for indication of the number of
relayings and the section 2505 for the initial setting value in the
section for indication of the number of relayings in the header portion,
and transmits this packet.
This packet for count of the number of node devices is similarly relayed by
the node devices II 602, III 603, and IV 604, and is received by the
terminal equipment I 545 connected to the node device I 601. The terminal
equipment I 545 connected to the node device I 601 is the server that
transmitted the packet for count of the number of node devices. The packet
processing unit 902 of the server reads the value in the section 2503 for
identification of the kind of packet. Since the section 2503 for
identification of the kind of packet stores the value indicating the
packet for count of the number of node devices, the packet processing unit
902 reads the value "4" stored in the section 2505 for the initial setting
value 2505 for the section of indication of the number of relayings, and
stores the read value as the number of node devices connected to the
network system. After reception of the packet for count of the number of
node devices, the server ends transmission of the packet for count of the
number of node devices.
In this embodiment, the node device to which the terminal equipment for
transmitting a packet is connected is considered as the first relaying
node device, and the node device which is the destination node device of
the packet, finally receives the packet, and outputs it to the terminal
equipment side is not considered as a relaying node device. However, the
last node device may also be considered as a relaying node device, and the
number of relayings of a packet and a value used for determining whether
each node device outputs a packet to the next node device or the terminal
equipment side (in this embodiment, when the value in the section for
indication of the number of relayings is "0", a packet is output to the
terminal equipment) can be set. For example, assuming that the destination
node device also decrements the value in the section for indication of the
number of relayings (for example, when a node device in which an insertion
means is arranged at the upstream side of a down counter and a separation
means is arranged at the downstream side of the down counter is used), the
server which performs the above-mentioned operation receives the packet
for count of the number of node devices which has passed twice the node
device to which the own terminal equipment is connected (when the packet
is transmitted and when it is received; the value in the section for
indication of the number of relayings is decremented twice by the node
device to which the own terminal equipment is connected). In this case, a
value obtained by subtracting "1" from the value in the section for the
initial setting value of the received packet for count of the number of
node devices indicates the number of node devices connected to the
network.
Subsequently, the server transmits a packet for notification of the number
of nodes for notifying all the terminal equipments of the network system
of the number of node devices connected to the network system. In this
process, the terminal equipment I 545 as the server connected to the node
device I 601 forms and transmits eight packets for notification of the
number of nodes in which a predetermined value is set in the sections 2503
for identification of the kind of packet, "1" is set in the sections 2501
for indication of the number of relayings of the header portion, and "1"
to "8" are respectively set in the sections for designation of the
wavelength in use. At this time, the value in the section 2501 for
indication of the number of relayings is written in the section 2505 for
the initial setting value in the section for indication of the number of
relayings, a value "1" indicating .lambda.1 as the reception wavelength of
the fixed wavelength reception unit I 504 that outputs a packet to the
separation-insertion unit I 512 to which the terminal equipment I 545 is
connected via the sub transmission path 537 is set in the section 2601 for
the reception wavelength of the server, and a value "11" as the
identification number of the terminal equipment I 545 is stored in the
section 2602 for identification of the server. In addition, the value "4"
calculated in the above-mentioned process is used in the section 2603 for
the number of all relaying node devices. These eight packets for
notification of the number of nodes are processed in the same manner as
the above-mentioned packet D for count of the number of node devices, and
are output to the buffer I 520. In the buffer I 520, the value "1" in the
section 2501 for indication of the number of relayings of each packet is
decremented to "0" by the down counter 1704, and the eight packets are
written in the memory regions I to VIII in accordance with the values in
the sections 2502 for designation of the wavelength in use of their header
portions. In this manner, after the eight packets for notification of the
number of node devices are written in the memory regions I to VIII, the
eight packets are transmitted from the variable wavelength transmission
units I 528 to the neighboring node device II 602 at the downstream side
using predetermined wavelengths set in their sections 2502 for designation
of the wavelength in use under the control of the wavelength control unit
and the buffer control unit in the control section 501.
The eight packets for notification of the number of node devices
transmitted to the node device II 602 are respectively received by the
fixed wavelength reception units I 504 to VIII 511 of the node device II
602 in accordance with the wavelengths indicated by the values set in
their sections 2502 for designation of the wavelength in use, are
separated by the separation-insertion units I 512 to VIII 519 in the same
manner as the packet D for count of the number of node devices, and are
then output to the terminal equipments I 545 to VIII 552 via the sub
transmission paths.
The terminal equipments I 545 to VIII 552 connected to the node device II
602 store a value "1" in the section 2505 for the initial setting value in
the section for indication of the number of relayings, a value "1" in the
section 2601 for the reception wavelength of the server, a value "11" in
the section for identification of the server, and a value "4" in the
section 2603 for the number of all relaying node devices of each received
packet for notification of the number of node devices.
Subsequently, the terminal equipment I 545 as the server similarly forms
and transmits eight packets for notification of the number of node devices
in which "2" is set in the sections 2501 for indication of the number of
relayings and the sections 2505 for the initial setting value in the
section for indication of the number of relayings of the header portion.
These eight packets for notification of the number of node devices are
processed by the node device I 601 in the same manner as described above,
and the value in the section 2501 for indication of the number of
relayings of each packet is decremented from "2" to "1". Thereafter, the
packets are output to the node device II 602. Since the value in the
section 2501 for indication of the number of relayings of each packet is
"1", the separation-insertion units of the node device II 602 do not
separate these eight packets but output them to the buffers. Thereafter,
the value in the section 2501 for indication of the number of relayings of
each packet is decremented from "1" to "0", and the packets are output
from the variable wavelength transmission units to the node device III
603. Since the value in the section 2501 for indication of the number of
relayings of each packet is "0", the node device III 603 separates these
packets and supplies them to the terminal equipments I 545 to VIII 552.
The packet processing units 902 of these terminal equipments similarly
store a value "2" in the section 2505 for the initial setting value in the
section for indication of the number of relayings, a value "1" in the
section 2601 for the reception wavelength of the server, a value "11" in
the section for identification of the server, and a value "4" in the
section 2603 for the number of all relaying node devices of each packet
for notification of the number of node devices.
Subsequently, the terminal equipment I 545 as the server similarly forms
and transmits eight packets for notification of the number of node devices
in which "3" is set in the sections 2501 for indication of the number of
relayings and the sections 2505 for the initial setting value in the
section for indication of the number of relayings of the header portion.
These eight packets for notification of the number of node devices are
similarly relayed by the node devices II 602 and III 603, and are received
by the eight terminal equipments 545 to 552 connected to the node device
IV 604. Then, the packet processing units 902 of these terminal equipments
store a value "3" in the section 2505 for the initial setting value in the
section for indication of the number of relayings, a value "1" in the
section 2601 for the reception wavelength of the server, a value "11" in
the section for identification of the server, and a value "4" in the
section 2603 for the number of all relaying node devices of each packet
for notification of the number of node devices.
Furthermore, the terminal equipment I 545 as the server similarly forms and
transmits eight packets for notification of the number of node devices in
which "4" is set in the sections 2501 for indication of the number of
relayings and the sections 2505 for the initial setting value in the
section for indication of the number of relayings of the header portion.
These eight packets for notification of the number of node devices are
similarly relayed by the node devices II 602, III 603, and IV 604, and are
received by the eight terminal equipments 545 to 552 connected to the node
device I 601. At this time, the packet processing units 902 of the
terminal equipments II 546 to VIII 552 connected to the node device I 601
similarly store a value "4" in the section 2505 for the initial setting
value in the section for indication of the number of relayings, a value
"1" in the section 2601 for the reception wavelength of the server, a
value "11" in the section for identification of the server, and a value
"4" in the section 2603 for the number of all relaying node devices of
each packet for notification of the number of node devices.
On the other hand, the terminal equipment I 545 connected to the node
device I 601 is the terminal equipment that transmitted the packet for
notification of the number of node devices. Since this packet for
notification of the number of node devices was relayed by all the node
devices of the network system and returned to the own terminal equipment
after traveling through the network once, the terminal equipment I 545
ends the transmission of the packets for notification of the number of
node devices upon reception of the packet for notification of the number
of node devices.
FIG. 29 is a flow chart showing the transmission operation of the packet
for notification of the number of node devices. At this time, since the
terminal equipment which transmits the packet for notification of the
number of node devices recognizes the number of all the node devices of
the network, the terminal equipment as the server may end the transmission
of the packet for notification of the number of node devices after it
transmits packets for notification of the number of node devices to the
respective node devices using their reception wavelengths. FIG. 30 is a
flow chart showing this operation.
A terminal equipment, which received the packet for notification of the
number of node devices, sends back a packet for report of the connection
form to the terminal equipment which generates the terminal equipment
connection table. Each terminal equipment sets a predetermined value
indicating the packet for report of the connection form in the section
2503 for identification of the kind of packet, and writes, in the section
2501 for indication of the number of relayings of the header portion, a
value obtained by subtracting the value in the section 2505 for the
initial setting value in the section for indication of the number of
relayings from the value "4" in the section for the number of all relaying
node devices stored upon reception of the packet for notification of the
number of node devices. In this case, if this subtraction yields "0", "4"
is set instead. In the terminal equipments connected to the node device II
602, this value becomes "3" since the value in the section 2505 for the
initial setting value in the section for indication of the number of
relayings is "1", as described above. On the other hand, in the terminal
equipments connected to the node device III 603, this value becomes "2".
Also, in the terminal equipments connected to the node device IV 604, this
value becomes "1". Furthermore, in the terminal equipments connected to
the node device I 601, this value becomes "4". In this manner, the section
for indication of the number of relayings of each packet stores
information indicating the number of relayings until the packet reaches
the server.
The section 2502 for designation of the wavelength in use stores the value
in the section 2601 for the reception wavelength of the server stored upon
reception of the packet for notification of the number of node devices.
The section 2505 for the initial setting value in the section for
indication of the number of relayings stores the same value as that in the
section 2501 for indication of the number of relayings. On the other hand,
the section 2701 for the reception wavelength of the terminal equipment
stores the value indicating the reception wavelength of the fixed
wavelength reception unit that outputs a packet to the
separation-insertion unit to which the own terminal equipment is connected
via the sub transmission path. Furthermore, the section 2702 for
identification of the terminal equipment stores the identification number
of the own terminal equipment. The packet for report of the connection
form which is generated in this manner is transmitted from each terminal
equipment and is received by the terminal equipment I 545 as the server.
Upon reception of the packets for report of the connection form, the
terminal equipment I 545 as the server generates a terminal equipment
connection table including the terminal equipment identification numbers
as the values in the sections 2702 for identification of the terminal
equipment, the values (the numbers of relayings) to be written in the
sections 2501 for indication of the number of relayings upon transmission
of packets to the respective terminal equipments, and the values
(reception wavelengths) to be written in the section 2502 for indication
of the wavelength in use. At this time, as the terminal equipment
identification numbers, the values in the sections 2702 for identification
of the terminal equipment of the received packets for report of the
connection form are used. Also, as the number of relayings, a value
obtained by subtracting the value in the section 2505 for the initial
setting value in the section for indication of the number of relayings of
each received packet for report of the connection form from the value "4"
in the section for the number of all relaying node devices is written. In
this case, if this subtraction yields "0", "4" is written instead. On the
other hand, as the reception wavelengths, the values in the sections 2701
for the reception wavelength of the terminal equipment of the received
packets for report of the connection form are written. In this manner, the
server generates a terminal equipment connection table shown in Table 4
below.
TABLE 4
______________________________________
Terminal
Equipment
Identification Number of
Reception
Number Relayings
Wavelength
______________________________________
11 -- --
12 4 2
13 4 3
14 4 4
15 4 5
16 4 6
17 4 7
18 4 8
21 1 1
22 1 2
23 1 3
24 1 4
25 1 5
26 1 6
27 1 7
28 1 8
31 2 1
32 2 2
33 2 3
34 2 4
35 2 5
36 2 6
37 2 7
38 2 8
41 3 1
42 3 2
43 3 3
44 3 4
45 3 5
46 3 6
47 3 7
48 3 8
______________________________________
The server which generated the terminal equipment connection table
transmits the generated terminal equipment connection table to the
respective terminal equipments as in the packets for notification of the
number of node devices. Upon reception of the terminal equipment
connection table, each terminal equipment generates a terminal equipment
connection table which can be used by itself on the basis of the received
terminal equipment connection table. As another method, since the terminal
equipment which generated the terminal equipment connection table first
already recognizes the connection forms of the respective terminal
equipments, it may modify its terminal equipment connection table in
correspondence with the respective terminal equipments and may transmit
the modified terminal equipment connection tables to the respective
terminal equipments.
On the other hand, a section for storing a copy of the value in the section
for designation of the wavelength in use may be assigned to the data
portion of the packet for notification of the number of node devices. With
this format, even when the terminal equipment itself does not recognize
its own reception wavelength, it can detect the reception wavelength based
on the value in the section for storing a copy of the value in the section
for designation of the wavelength in use of the received packet for
notification of the number of node devices.
(Eighth Embodiment)
FIG. 31 shows the format of a packet for count of the number of node
devices according to the eighth embodiment of the present invention, which
packet is suitably used in a terminal equipment connection table
generation method in the above-mentioned multihop system.
Referring to FIG. 31, sections 2501, 2502, 2503, and 2506 are the same as
those in the seventh embodiment. A section 3101 for count of the number of
relayings is used for counting the number of relayings. Each node device
which relays and transmits the packet for count of the number of node
devices increments the value in this section 3101 by "1" to generate a new
packet for count of the number of node devices, and relays the packet.
FIG. 32 is a flow chart showing the operation of the terminal equipment as
the source of the packet for count of the number of node devices in the
eighth embodiment of the present invention.
FIG. 33 is a flow chart showing the operation of the terminal equipment
which receives the packet for count of the number of node devices in the
eighth embodiment of the present invention.
In this embodiment, the terminal equipment as the source of the packet for
count of the number of node devices sets "1" in the section for indication
of the number of relayings and "1" in the section for designation of the
wavelength in use, and transmits the packet for count of the number of
node devices to only a specific terminal equipment connected to the
neighboring node device at the downstream side.
The terminal equipment which received this packet for count of the number
of relayings re-sets the value in the section 3101 for count of the number
of relayings in the received packet for count of the number of node
devices by incrementing the value by "1", and similarly transmits this
packet for count of the number of node devices to only a specific terminal
equipment connected to the neighboring node device at the downstream side.
In this manner, the packet for count of the number of node devices is
transmitted in turn to terminal equipments having the same reception
wavelength as the transmission wavelength of the terminal equipment as the
source of the packet for count of the number of node devices and connected
to the neighboring node devices at the downstream side. When the terminal
equipment as the source of the packet for count of the number of node
devices receives the packet for count of the number of node devices, the
transmission process of the packet for count of the number of node devices
ends. The source of the packet for count of the number of node devices can
detect the number of all the node devices on the basis of the value set in
the section for count of the number of relayings. Thereafter, the
subsequent process is executed as in the seventh embodiment.
In this embodiment, since the number of packets for count of the number of
node devices transmitted from the terminal equipment as the source of the
packet for count of the number of node devices becomes small and the
packet for count of the number of node devices is transmitted from a
plurality of terminal equipments, the load upon transmission of the packet
for count of the number of node devices can be reduced.
As described above, the present invention reveals the method of checking
the form of the network by the terminal equipment. In the terminal
equipment connection table generation method according to the present
invention, for example, the terminal equipment connection table can be
generated by acquiring terminal equipment connection information via
communications of the network system without looking up the terminal
equipment connection table. For this reason, even when none of the
terminal equipments have a terminal equipment connection table (for
example, when a new network system is constituted or when the arrangement
of the network system is changed), the terminal equipment connection
tables of all the terminal equipments connected to the network system need
not be manually created or updated using input/output units, thus easily
and accurately generating terminal equipment connection tables.
Furthermore, when the network system has a large scale and a large number
of terminal equipments are connected over a broad area, terminal equipment
connection tables can be easily and accurately generated.
(Ninth Embodiment)
FIG. 34 shows the format of a packet for register request according to the
ninth embodiment of the present invention, which packet is suitably used
in the above-mentioned multihop system. When a new terminal equipment is
connected to the network system or the connection condition of the
terminal equipment is changed, the packet for register request is
transmitted from the terminal equipment to the existing terminal
equipments, and the terminal equipments that received this packet register
new data in their terminal equipment connection tables.
Referring to FIG. 34, a section 3401 for indication of the number of
relayings indicates the number of relayings required for transmitting a
packet from the source node device to the destination node device. Each
node device can detect based on the value in the section 3401 for
indication of the number of relayings whether or not the neighboring node
device at the downstream side in the transmission direction is the
destination node device. Furthermore, each node device can detect whether
or not a terminal equipment connected to the own node device is the
destination by checking if this value is "0". A section 3402 for
designation of the wavelength in use designates the wavelength to be used
in the relaying transmission operation. As the value used in the section
3402 for designation of the wavelength in use of this header portion, "1"
to "8" are assigned in correspondence with transmission wavelengths
.lambda.1 to .lambda.8, as shown in Table 2 above. A section 3403 for
identification of the kind of packet indicates the kind of packet. In this
case, a value indicating the packet for register request is set in the
section 3403. The header portion includes a remaining header portion 3404.
The section 3401 for indication of the number of relayings, the section
3402 for designation of the wavelength in use, the section 3403 for
identification of the kind of packet, and the remaining header portion
3404 constitute the header portion.
A section 3405 for the initial setting value in the section for indication
of the number of relayings stores a value set in the section 3401 for
indication of the number of relayings by the terminal equipment as the
source of the packet for register request. A section 3406 for the
reception wavelength of the terminal equipment newly registered stores one
of values indicating the wavelengths (to be simply referred to as
reception wavelengths hereinafter) received by the fixed wavelength
reception units 504 to 511, which output packets to the
separation-insertion units 512 to 519 to one of which the terminal
equipment as the source of the packet for register request is connected
via one of the sub transmission paths 537 to 544. A section 3407 for
identification of the terminal equipment newly registered stores a value
indicating the terminal equipment identification number of the terminal
equipment as the source of the packet for register request. The packet
includes a remaining data portion 3408. The section 3405 for the initial
setting value in the section for indication of the number of relayings,
the section 3406 for the reception wavelength of the terminal equipment
newly registered, the section 3407 for identification of the terminal
equipment newly registered, and the remaining data portion 3408 constitute
a data portion to be carried by this packet.
FIG. 35 shows the format of a packet for transfer request according to the
present invention. In the packet for transfer request, a value indicating
the packet for transfer request as the kind of packet is stored in a
section for identification of the kind of packet. A data portion includes
the section 3407 for identification of the terminal equipment newly
registered.
FIG. 36 is a flow chart showing the operation of the terminal equipment as
the source of the packet for register request of this embodiment.
FIG. 37 is a flow chart showing the operation of the terminal equipment
which receives the packet for register request of this embodiment.
An embodiment of a terminal equipment registration method using the packet
for register request and the packet for transfer request according to the
present invention will be described below. In the following description, a
case will be exemplified wherein the terminal equipment I 545 connected to
the node device I 601 is newly connected to the network system in the
arrangement of the network system shown in FIG. 6 using the arrangement of
the node device shown in FIGS. 5A and 5B. Also, in the following
description, the same constituting elements in different terminal
equipments are denoted by the same reference numerals as in FIGS. 5A, 5B,
6, 9, 16, and 17, for the sake of convenience.
The terminal equipment I 545 as a terminal equipment to be newly registered
connected to the node device I 601 forms a packet for register request in
which "1" is set in the section 3401 for indication of the number of
relayings and "1" is set in the section for designation of the wavelength
in use of the header portion, and transmits this packet to the
separation-insertion unit I 512 of the node device I 601 via the sub
transmission path I 537. At this time, the section 3405 for the initial
setting value in the section for indication of the number of relayings of
the packet for register request stores a value "1", the section 3406 for
the reception wavelength of the terminal equipment newly registered stores
a value "1" indicating .lambda.1 as the reception wavelength of the fixed
wavelength reception unit I 504 that outputs a packet to the
separation-insertion unit I 512 to which the terminal equipment I 545 is
connected via the sub transmission path I 537, and the section 3407 for
identification of the terminal equipment newly registered stores a value
indicating the identification number of the terminal equipment I 545. In
the following description, this packet will be referred to as a packet E.
The I/F unit 1603 of the separation-insertion unit I 512 of the node device
I 601 writes the packet E for register request transmitted via the sub
transmission path I 537 in the FIFO I 1606. Upon completion of the writing
operation of the packet E for register request in the FIFO I 1606, the
insertion control unit 1605 detects a division of a packet flow which is
being read out from the FIFO II 1607, switches the input source of the
selector 1608 to the FIFO I 1606, stops the reading operation of the FIFO
II 1607, and starts a reading operation of the FIFO I 1606. Thereafter,
upon completion of the reading operation of the packet E for register
request written in the FIFO I 1606, the insertion control unit 1605
switches the input source of the selector 1608 to the FIFO II 1607 again,
stops the reading operation of the FIFO I 1606, and restarts a reading
operation of the FIFO II 1607. The packet E for register request output
from the selector 1608 is input to the buffer I 520.
The demultiplexer 1701 of the buffer I 520 outputs the value in the section
3402 for designation of the wavelength in use of the header portion of the
packet E for register request to the latch I 1702, the value in the
section 3401 for indication of the number of relayings to the latch II
1703, and the data portion to the shift register 1705. The latch I 1701
stores the value in the section for designation of the wavelength in use
of the head portion of the packet E for register request, and outputs the
stored value to the writing address counter 1706 and the selector 1707.
The latch II 1703 stores the value in the section 3401 for indication of
the number of relayings of the header portion of the packet E for register
request, and outputs the stored value to the down counter 1704. The value
"1" in the section 3401 for indication of the number of relayings of the
header portion of the packet E for register request output from the latch
II 1703 is decremented to "0" by the down counter 1704, and the
decremented value is output to the selector 1707. The shift register 1705
delays the data portion of the packet E for register request output from
the demultiplexer 1701 by a required period of time, and outputs the
delayed data portion to the selector 1707. The selector 1707 re-constructs
the packet E for register request with the decremented value in the
section 3401 for indication of the number of relayings by sequentially
selecting the value in the section 3402 for designation of the wavelength
in use of the header portion of the packet E for register request output
from the latch I 1702, the decremented value in the section 3401 for
indication of the number of relayings output from the down counter 1704,
and the delayed data portion of the packet E for register request output
from the shift register 1705. The selector 1707 outputs the re-constructed
packet to the dual port memory 1709. On the other hand, the writing
address counter 1706 sets the writing start address of the dual port
memory 1709 in which the packet E for register request is to be written in
accordance with the value "1" in the section 3402 for designation of the
wavelength in use of the packet E for register request output from the
latch I 1702, and sequentially outputs writing address signals to the dual
port memory 1709. The input port of the dual port memory 1709 receives the
re-constructed packet E for register request via the selector 1707, and
the packet E is sequentially written in the memory region I in accordance
with the addresses output from the writing address counter 1706.
After the packet E for register request is written in the memory region I,
when the transmission wavelength of the variable wavelength transmission
unit I 528 is set to be .lambda.1 under the control of the wavelength
control unit in the control section 501, the buffer control unit in the
control section 501 outputs an offset value A1 corresponding to the memory
region I to the reading address counter 1708 of the buffer I 520. Based on
the offset value A1, the reading address counter 1708 generates addresses
for reading out the packet E for register request written in the memory
region I by incrementing a counter, and outputs the addresses to the dual
port memory 1709. The packet E for register request is read out from the
output port of the dual port memory 1709 in accordance with the reading
addresses, and is output to the variable wavelength transmission unit I
528. Since the transmission wavelength of the variable wavelength
transmission unit I 528 is set to be .lambda.1, the packet E for register
request is output from the variable wavelength transmission unit I 528 to
the wavelength multiplexer 536 as an optical signal of the wavelength
.lambda.1, and is multiplexed by the wavelength multiplexer 536 with
optical signals of different wavelengths output from other variable
wavelength transmission units II 529 to VIII 535. The multiplexed signal
is output onto the optical fiber 502, and is transmitted to the
neighboring node device II 602 at the downstream side.
The packet E for register request transmitted to the node device II 602 as
the optical signal of the wavelength .lambda.1 is received by the fixed
wavelength reception unit I 504 of the node device II 602, and is output
to the separation-insertion unit I 512. The latch 1602 of the
separation-insertion unit I 512 stores the value in the section 3401 for
indication of the number of relayings of the packet E for register request
output from the fixed wavelength reception unit I 504, and outputs the
stored value to the comparator 1601. Since the value in the section 3401
for indication of the number of relayings of the packet E for register
request output from the latch 1602 is "0", the comparator 1601 outputs a
separation instruction to the demultiplexer 1604. Upon reception of the
separation instruction from the comparator 1601, the demultiplexer 1604
outputs the input packet E for register request to the I/F unit 1603.
Thus, the packet E for register request is output to the I/F unit 1603 and
is transmitted via the sub transmission path I 537. Thereafter, the packet
E is received by the terminal equipment I 545 as the destination, and the
packet processing unit 902 reads the value in the section 3403 for
identification of the kind of packet of the header portion. Since this
section stores a value indicating the packet for register request, the
packet processing unit 902 newly registers information of the terminal
equipment I 545 connected to the node device I 601 in the terminal
equipment connection table 903 using the value in the section 3405 for the
initial setting value in the section for indication of the number of
relayings, the value in the section 3406 for the reception wavelength of
the terminal equipment newly registered, and the value in the section 3407
for identification of the terminal equipment newly registered in the data
portion of this packet. At this time, as the value of the number of
relayings in Table 2 above, a value "3" obtained by subtracting the value
"1" in the section 3405 for the initial setting value in the section for
indication of the number of relayings from the value "4" indicating the
number of node devices connected to the network system is set.
In this manner, the terminal equipment I 545 connected to the node device I
601 as the source of the packet for register request is registered in the
terminal equipment connection table 903 of the terminal equipment I 545
connected to the node device II 602.
After the first packet E for register request is transmitted, the terminal
equipment I as a terminal equipment to be newly registered connected to
the node device I 601 forms seven packets for register request in which
"1" is set in the sections 3401 for indication of the number of relayings
and "2" to "8" are respectively set in the sections 3402 for designation
of the wavelength in use, and transmits these packets to the
separation-insertion unit I 512 of the node device I 601 via the sub
transmission path I 537 in the same manner as the above-mentioned packet E
for register request. At this time, the values in the sections 3405 for
the initial setting value in the section for indication of the number of
relayings, the sections 3406 for the reception wavelength of the terminal
equipment newly registered, and the section 3407 for identification of the
terminal equipment newly registered of the seven packets for register
request are the same as those in the packet E for register request. These
seven packets for register request are processed in the same manner as the
packet E for register request, and are output from the
separation-insertion unit I 512 to the buffer I 520. In the buffer I 520,
the value "1" in the section 3401 for indication of the number of
relayings of each packet is decremented to "0" by the down counter 1704,
and thereafter, the seven packets for register request are written in the
memory regions II to VIII in accordance with the values in the sections
3402 for designation of the wavelength in use of their header portions.
After the seven packets for register request are written in the memory
regions II to VIII in this manner, these packets are transmitted from the
variable wavelength transmission unit I 528 to the neighboring node device
II 602 at the downstream side using predetermined wavelengths set by the
values in their sections 3402 for designation of the wavelength in use
under the control of the wavelength control unit and the buffer control
unit in the control section 501.
The seven packets for register request transmitted to the node device II
602 are respectively received by the fixed wavelength reception units II
505 to VIII 5111 in accordance with the wavelengths set by the values in
their sections 3402 for designation of the wavelength in use, and are
separated by the separation-insertion units II 513 to VIII 519 in the same
manner as the first packet E for register request. Then, the packets are
output to the terminal equipments II 546 to VIII 552 via the sub
transmission paths. In each of the terminal equipments II 546 to VIII 552,
the terminal equipment I connected to the node device I 601 is newly
registered in the terminal equipment connection table 903 as in the packet
E for register request.
In this manner, the terminal equipment I 545 as the source of the packet
for register request connected to the node device I 601 is registered in
the terminal equipment connection tables 903 in the terminal equipments I
545 to VIII 552 connected to the node device II 602.
Subsequently, the terminal equipment I 545 as a terminal equipment to be
newly registered connected to the node device I 601 forms and transmits
eight packets for register request in which "2" is set in the section 3401
for indication of the number of relayings of the header portion, and "1"
to "8" are set in the sections 3402 for designation of the wavelength in
use. At this time, the values in the section 3405 for the initial setting
value in the section for indication of the number of relayings, the
section 3406 for the reception wavelength of the terminal equipment newly
registered, and the section 3407 for identification of the terminal
equipment newly registered of each of the eight packets for register
request are the same as those in the packet E for register request. These
eight packets for register request are processed by the node device I 601
in the same manner as the above-mentioned packet E for register request,
and the value in the section 3401 for indication of the number of
relayings of each packet is decremented from "2" to "1". Thereafter, the
eight packets are output to the node device II 602. In this embodiment,
since each node device can output packets using desired wavelengths
independently of their reception wavelengths, the wavelengths need not be
designated when the packets are output from the node device I 601 to the
node device II 602. Since the value in the section 3401 for indication of
the number of relayings of each packet is "1", the separation-insertion
units 512 to 519 of the node device II 602 do not separate the packets but
output them to the buffers 520 to 527. After the value in the section 3401
for indication of the number of relayings of each packet is decremented
from "1" to "0", the packets are output from any one of the variable
wavelength transmission units 528 to 535 to the node device III 603. In
the node device III 603, since the value in the section 3401 for
indication of the number of relayings of each packet is "0", the packets
are separated and are transmitted to the terminal equipments I 545 to VIII
552 to be subjected to the same new registration processing as described
above. In this manner, the terminal equipment I as the source of the
packet for register request connected to the node device I 601 is
registered in the terminal equipment connection tables 903 in the terminal
equipments I 545 to VIII 552 connected to the node device III 603.
Subsequently, the terminal equipment I 545 as a terminal equipment to be
newly registered connected to the node device I 601 forms and transmits
eight packets for register request by setting "3" in the sections 3401 for
indication of the number of relayings of the header portions.
These eight packets for register request are similarly relayed by the node
devices II 602 and III 603, and are received by the eight terminal
equipments 545 to VIII 552 connected to the node device IV 604. In this
manner, the terminal equipment I 545 as the source of the packet for
register request connected to the node device I 601 is registered in the
terminal equipment connection tables 903 in the terminal equipments I 545
to VIII 552 connected to the node device IV 604.
Furthermore, the terminal equipment I 545 as a terminal equipment to be
newly registered connected to the node device I 601 forms and transmits
eight packets for register request by setting "4" in the sections 3401 for
indication of the number of relayings of the header portions.
These eight packets for register request are similarly relayed by the node
devices II 602, III 603, and IV 604, and are received by the terminal
equipments I 545 to VIII 552 connected to the node device I 601. At this
time, in the terminal equipments II 546 to VIII 552 connected to the node
device I 601, the terminal equipment I 545 is registered in the terminal
equipment connection tables 903. In this case, the value of the number of
relayings is set to be "4" corresponding to the number of node devices
since the value obtained by subtracting the value "4" in the section 3405
for the initial setting value in the section for indication of the number
of relayings from the value "4" indicating the number of node devices
connected to the network system becomes "0".
On the other hand, the terminal equipment I 545 connected to the node
device I 601 is the terminal equipment which transmitted the packet for
register request. Since this packet for register request was relayed by
all the node devices on the network system and returned to the own
terminal equipment after completing its journey through the network once,
the terminal equipment I 545 ends the transmission of the packet for
register request upon reception of the packet for register request.
Thereafter, the terminal equipment I 545 as a terminal equipment to be
newly registered connected to the node device I 601 forms and transmits a
packet for transfer request in which "1" is set in the section 3401 for
indication of the number of relayings of the header portion, "1" is set in
the section 3402 for designation of the wavelength in use, and a value
indicating the identification number of the terminal equipment I 545 is
set in the section 3407 for identification of the terminal equipment newly
registered.
The packet for transfer request is transmitted to the terminal equipment I
545 connected to the node device II 602, which neighbors the node device I
601. The packet processing unit 902 reads the value in the section for
identification of the kind of packet of the header portion. Since the
value indicating the packet for transfer request is set in this section,
transfer processing of the terminal equipment connection table 903 is
performed. The packet processing unit 902 searches the terminal equipment
connection table 903 using the value in the section 3407 for
identification of the terminal equipment newly registered of the data
portion of the packet, and forms a packet (transfer packet) in which "3"
is set in the section 3401 for indication of the number of relayings of
the header portion, "1" is set in the section for designation of the
wavelength in use, and the terminal equipment connection table 903 in the
data portion. Then, the packet processing unit 902 transmits the formed
packet to the terminal equipment I 545 connected to the node device I 601.
The transfer packet is received by the terminal equipment I 545 connected
to the node device I 601, and the table stored in the packet is used as
the terminal equipment connection table 903. In this case, this table is
modified in correspondence with the terminal equipment I 545 connected to
the node device I 601, and information (terminal equipment identification
number, number of relayings, and reception wavelength) of the terminal
equipment 545 connected to the node device II 602 is also added to the
table. Then, the table is stored as the terminal equipment connection
table 903. In this case, a terminal equipment to which a packet for
transfer request is transmitted is not limited to the terminal equipment I
545 connected to the node device II 602 which neighbors the node device I
601. However, this terminal equipment is selected as the closest one.
The above-mentioned operations are shown in the operation flow charts of
FIGS. 36 and 37. (10th Embodiment)
FIG. 38 is a flow chart showing the operation of the terminal equipment as
the source of a packet for register request in the 10th embodiment of the
present invention.
FIG. 39 is a flow chart showing the operation of the terminal equipment
which receives the packet for register request in the 10th embodiment of
the present invention.
In the 10th embodiment, the terminal equipment as the source of a packet
for register request transmits packets for register request in which "1"
is set in the sections 3401 for indication of the number of relayings and
"1" to "8" are set in the sections 3402 for designation of the wavelength
in use to only the eight terminal equipments connected to the neighboring
node deice at the downstream side. The terminal equipments which received
these packets for register request register the information of the source
terminal equipment in their terminal equipment connection tables as in the
ninth embodiment. Furthermore, the terminal equipment whose reception
wavelength is the same as that of the source terminal equipment of the
packet for register request re-sets the packets by adding "1" to the value
of the section 3405 for the initial setting value in the section for
indication of the number of relayings of the received packet for register
request, and transmits the packets to only the terminal equipments
connected to the neighboring node device at the downstream side. In this
manner, the terminal equipment whose reception wavelength is the same as
that of the source terminal equipment of the packet for register request
transmits packets for register request to the terminal equipments
connected to the neighboring node device at the downstream side. When the
terminal equipment as the source of the packet for register request
receives the packet for register request, it ends the transmission of the
packet for register request, and then performs, e.g., transmission of a
packet for transfer request as in the ninth embodiment.
The above-mentioned operations are shown in the operation flow charts of
FIGS. 38 and 39.
In this embodiment, since the number of packets for register request to be
transmitted from the source terminal equipment of a packet for register
request can be reduced, and a packet for register request is transmitted
from a plurality of terminal equipments, the load upon transmission of the
packet for register request can be reduced.
Upon execution of the operations of the ninth embodiment, if the packet for
register request transmitted from the own terminal equipment is received
before the packets for register request to be transmitted are transmitted
to all the terminal equipments (such an error tends to occur especially
when the number of node devices or the number of wavelengths is small),
transmission of the packet for register request undesirably ends at that
time, and the packet for register request can no longer be transmitted
even if more destinations to which the packet for register request need be
transmitted still remain (in particular, other terminal equipments
connected to the node device to which the register request terminal
equipment is connected). In order to solve this problem, a packet for
register request to be transmitted to the respective node devices using a
wavelength that can be received by the own terminal equipment (.lambda.1
in the ninth embodiment) is sent after packets for register request
transmitted using other wavelengths. For example, in the ninth embodiment,
when packets for register request in which the value in the section for
designation of the wavelength in use is sequentially changed while the
value in the section for indication of the number of relayings is fixed
are output from the register request terminal equipment, the value to be
set in the section for designation of the wavelength in use can be changed
in the order of, e.g.,
2.fwdarw.3.fwdarw.4.fwdarw.5.fwdarw.6.fwdarw.7.fwdarw.8.fwdarw.1, so that
"1" indicating the wavelength that can be received by the source is set
last. The same applies to the 10th embodiment. However, in the sixth
embodiment, if there are two or more node devices, the register request
terminal equipment receives a packet relayed by another terminal equipment
(not limited to a terminal equipment as long as the means used can process
and transmit a packet) as a packet for register request transmitted by the
own terminal equipment, the wavelength that can be received by the
register request terminal equipment must be designated for the relaying
terminal equipment. Alternatively, the need for this designation can be
obviated if terminal equipments that can receive the same wavelength as
the reception wavelength of the register request terminal equipment are
used as the relaying terminal equipments.
In the above embodiment, a packet is broadcasted by relaying the packet
from the register request terminal equipment to the respective node
devices. The value in the section for indication of the number of
relayings is set so that the node device to which the destination terminal
equipment in which the source terminal equipment is to be registered is
connected receives a packet in which information indicating the number of
relayings becomes "0". However, another appropriate value may be used
instead, and the number of relayings may be set by considering, as a
relaying node device, the node device to which the destination terminal
equipment in which the source terminal equipment is to be registered is
connected.
As described above, in the connection information (terminal equipment and
the like) registration method according to the present invention, since a
packet for register request can be transmitted via the network system, the
need for manual registration using input/output units of the terminal
equipments can be obviated, and registration can be easily and accurately
attained.
Furthermore, the source terminal equipment can detect that the packets for
register request are transmitted to all the terminal equipments since the
packet for register request transmitted from the own terminal equipment is
transmitted thereto. For this reason, completion of transmission of
packets for register request to all the terminal equipments can be easily
detected.
As described above, one characteristic feature of the present invention is
that a packet has information with which a node device can discriminate
whether an input packet is to be output to another node device or is to be
output to a sub transmission path, without comparing the destination
address of the packet with the address of the sub transmission path (or
the address of the terminal equipment connected to the sub transmission
path).
In the arrangement of the first and second embodiments, the two output
directions can be determined depending on whether or not the packet has a
section for designation of the wavelength in use of the relaying node
device. In the arrangement of the third and subsequent embodiments, the
two output directions can be determined depending on whether or not the
value in the section for indication of the number of relayings matches a
given value ("0" in the above embodiments). The number of sections for
indicating the number of relayings and the value indicating the number of
relayings can be appropriately determined.
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